Merge pull request #1022 from tweise/hds

random write test
Merge pull request #1026 from tweise/hds

Support sharing comparator with memory store.
Make test case work
WAL cleanup and metadata management.

- Remove unnecessary WAL metadata, keep only head and tail pointers.
- Store WAL metadata as part of HDSBucketManager check-pointed state.
- Cleanup old WAL files once tuples from them are written to data files.
Merge branch 'hds' of github.com:DataTorrent/Malhar into hds
Merge pull request #1027 from tushargosavi/hds

Hds - WAL changes
Rearange code
Merge branch 'hds' of github.com:DataTorrent/Malhar into hds
Add DTFile and performance test for DTFile
Make a copy of committed window id and offset in endWindow, and write it to WAL
metadata at end of write.
Merge pull request #1030 from siyuanh/hds

Add DTFile and performance test for DTFile
SPOI-3016 #comment Add documents and DTFile wrapper for HDSFileAccess
API
Merge pull request #1031 from siyuanh/hds

SPOI-3016 #comment Add documents and DTFile wrapper for HDSFileAccess
Merge branch 'hds' of github.com:DataTorrent/Malhar into hds
Check committed window id for data files and do not attempt recovery
if checkpointed window id is less than committed windowid.
Adding configuration settings for block size, compression, and cache configuration to HFile implementation
Merge pull request #1035 from sashadt/hds

Adding configuration settings for block size, compression, and cache con...
Merge pull request #1034 from tushargosavi/hds

Hds
Add logging to track bucket ownership.