This closes #680

    deleted VertexWithValue type;
    deleted InaccessibleMethodException; if the options are not set, -1 is returned;
    added missing javadocs;
    added tests;
    renamed type parameters VertexKey -> K, VertexValue -> VV, EdgeValue -> EV.

This commit squashes the following:

Pratially addressed inline comments

Added test for removal of a non-SP-edge

Removed trailing splits into vertex key and value

Made the extensions optional and separate

Removed overhead when the options are not used

Added Algorithm end string to the library methods

This closes #625

Closes #676

The system operators are, for example, the StreamDiscretizer and
WindowBuffer

[runtime] Fix for task canceling the order of (1) resource deregistration (2) completeness notification

[FLINK-1952] [tests] Add a test that runs an iterative job after a failure in another iterative job.

This test validates that task slots in co-location constraints are properly freed in the presence of failures.

This closes #566

As previous discussions before, we do not restrict max chars per line for Java code, but this one just way too long compare to others that I just think make easier to read if we wrap it.

Author: hsaputra <hsaputra@apache.org>

Closes #683 from hsaputra/wrap_very_long_line_in_FlatMapOperator and squashes the following commits:

37d2081 [hsaputra] Wrap very long line in FlatMapOperator class.

[FLINK-2006] [tests] Fix "TaskManagerTest.testRunJobWithForwardChannel()" by properly deploying receiver only after sender is running.

This squashes the following commits:

Split Iteration Configuration into VertexCentric/GSAConf

Fixed checkstyle errors

This closes #635

This closes #667

This closes #679

This closes #653

[FLINK-1711] Converted all usages of commons validate to guava checks(for Java classes), scala predef require(for scala classes)

This closes #673

[FLINK-1525] Implement a tool for parsing input parameters and provide facilities to use them in the system.

This closes #664

This closes #663

This closes #675