Ensure writer errors are propagated.
Add test for async exception propagation.
Convert to absolute path.
Fix serialization issues.
Reader retry on data file rewrite.
Fix invalid query result when key not present.
Merge pull request #1059 from tweise/hds

Fix invalid query result when key not present.
Fixing key de-serialization order of publisherId,advertizerId,adUnit
Merge branch 'hds' of github.com:Datatorrent/Malhar into hds