Initial commit of adding histogram functionality to the DoubleRDDFunctions.
Add tests for the Java implementation.
CR feedback
Remove extranious type definitions from inside of tests
Remove extranious type declerations
Remove explicit boxing
Add spaces
Added unit tests for size estimation for specialized hash sets and maps.
Incorporated ideas from pull request #200.
- Use Murmur Hash 3 finalization step to scramble the bits of HashCode
  instead of the simpler version in java.util.HashMap; the latter one
  had trouble with ranges of consecutive integers. Murmur Hash 3 is used
  by fastutil.

- Don't check keys for equality when re-inserting due to growing the
  table; the keys will already be unique

- Remember the grow threshold instead of recomputing it on each insert
Merge pull request #204 from rxin/hash

OpenHashSet fixes

Incorporated ideas from pull request #200.
- Use Murmur Hash 3 finalization step to scramble the bits of HashCode
  instead of the simpler version in java.util.HashMap; the latter one
  had trouble with ranges of consecutive integers. Murmur Hash 3 is used
  by fastutil.
- Don't check keys for equality when re-inserting due to growing the
  table; the keys will already be unique.
- Remember the grow threshold instead of recomputing it on each insert

Also added unit tests for size estimation for specialized hash sets and maps.
Fix the test
Merge pull request #86 from holdenk/master

Add histogram functionality to DoubleRDDFunctions

This pull request add histogram functionality to the DoubleRDDFunctions.