[streaming] ConnectedDataStream API  and operator cleanup + modified windowReduceGroup functionality

[streaming] Added CoBatchReduceInvokable, CoWindowReduceInvokable, CoGroupedBatchReduceInvokable, CoGroupedWindowReduceInvokable

- Clean dependencies in flink-streaming connectors

[FLINK-1117] Clean up flink-avro project: remove deprecated AvroRecord format, migrate tests to new java api.

  - add "flink-shading" for shaded libraries (currently guava only)
  - relocate guava in all projects and exclude it from the lib and exported dependencies
  - Exlude unnecessary transitive dependencies from hadoop 1

Clean minor javadoc errors.

[FLINK-1005] Extend TypeSerializer interface to handle non-mutable object deserialization more efficiently.

Improved Java TPCH query examples
Removed RelationalQuery Java API example

It is no longer a special-case operator that can only be used in front
of map-style operations.

We'll still ship the Logback configuration file and pass them their path to the JVM so that
users can use Flink with Logback as well.

This closes #125

Remove unnecessary type check and cast for FileInputSPlit.

Update LOG.debug to user SLF4J parameterized logging or protected by LOG.isDebugEnabled to save toString and String concat.

Remove unnecessary semicolons.

This closes #127

This closes #113

Checkstyle doesn't seem to support Java 8 yet.

Checking for Java support

Small changes and meaningful exception for unsupported compilers

pom.xml modified to use JDT compiler

Project structure refactored, examples added

Documentation added

Quickstart adapted

Also update documentation accordingly.