This squashes the following commits:

[gelly] Removed trailing comment

[gelly] Made remove methods use a coGroup fun

This closes #728

Added tables for parameter values

Adds links to optimization parameter values in the description

This closes #715.

The FlinkMiniCluster contain member variable called HOSTNAME which all caps. The naming of al caps usually reserved for constants and static variable.

The PR is changing the name of the variable and the usages.

Author: hsaputra <hsaputra@apache.org>

Closes #711 from hsaputra/update_hostname_to_match_conventions and squashes the following commits:

2a2f3bd [hsaputra] Change FlinkMiniCluster#HOSTNAME to FlinkMiniCluster#hostname to match naming convention.

This closes #718

 - Streaming mode sets the memory manager to lazy memory allocation to ensure
   heap is not blocked by batch memory manager

[FLINK-2085] [runtime] Add an option to let the MemoryManager allocate and release memory as needed.

This is an alternative mode to the current mode that pre-allocates all memory.

The default remains to pre-allocate all memory.

This closes #689

[FLINK-2053] [ml] Adds automatic type registration of flink-ml types. Adds de-duplication of registered types at ExecutionConfig. Fixes bug in Breeze SparseVector to Flink SparseVector conversion.

This closes #723.

This closes #714.

Before this, a sliding time window would keep emitting the last result
because the number of elements per pre-aggregation result was not
correctly reset on eviction.

Problem: Failures in the network stack were not properly handled and correctly
attributed.

Solution: Failures are always attributeed to the client (consumer). This change
introduces TransportException, which indicates whether the problem ocurred
locally or remotely. This makes it easy to reason about the source of a problem.

This closes #713.

Closes #697

This was using != before, now uses !(a.equals(b))

Problem: cancelling of tasks sometimes leads to misleading error messages about
"not found partitions". This is an artifact of task cancelling. If a task
(consumer) consumes data from another remote task (producer), its sends a
partition request over the network. If the producer fails concurrently with this
request, the request returns with a PartitioNotFoundException to the consumer.
If this error message is received *before* the consumer is cancelled (as a
result of the failing producer), you see the misleading error being attributed
to the consumer. This makes it hard to trace the root cause of the problem (the
failing producer).

Solution: when a consumer receives a remote PartitionNotFoundException, it asks
the central job manager whether the producer is still running or has failed.

If the producer is still running, the partition request is send again (using an
exponential back off). If the following requests fail again, the consumer fails
with a PartitionNotFoundException.

If the producer has failed, the consumer is cancelled.

If the producer is not running and has not failed, there is a bug either in the
consumer task setup (e.g. requesting a non-existing result) or in the network
stack (e.g. unsafe publication of produced results), in which case the error is
attributed to the consumer.

---

The new Akka messages introduced with this change are only exchanged in error
cases and don't affect normal operation.

Normal operation (not affected by this change):
	- TM1=>TM2: request result
	- TM2=>TM1: result

Error case:
	- TM1=>TM2: request result
	- TM2=>TM1: PartitionNotFoundException
	- TM1=>JM: check partition state
	- JM=>TM1: retrigger request -OR- cancel consumer

This closes #705.

Adds pipeline comments

Adds pipeline IT case

[FLINK-2050] [ml] Introduces new pipelining mechanism using implicit classes to wrap the algorithm logic

This closes #704.

Also added attribution for some of the Latex in optimization framework.

This closes #688.

Added test case for convergence

This closes #692.

This closes #698

This closes #682

 - Exclude static fields in Scala Pojo analysis
 - Recognize Java Tuples
 - Clean up legacy code

(And also make one of the field type retrieval methods nicer)

This closes #669

Improve type safety.
Minor cleanups in ProjectOperator.