append to Cascading frameworks system property instead of setting it directly.
Allow a limit to be specified for the number of open files used by a partitioned source
Enforce invariant: mapGroup iterators all nonempty

Previously not all fixes in mapGroup were covered
Merge pull request #1076 from fs111/develop

append to Cascading frameworks system property instead of setting it directly
Use option instead of default value.  This change also means that users can specify a threshold less than or equal to zero.  There doesn't seem to be any error checking in Cascading that forbids this, but the end result is that it's as if they passed in a threshold of 1.
Previous commit was incomplete and caused build to fail.  This will fix it...
Merge pull request #1078 from matt-martin/PartitionSourcesWithFileLimit

Allow PartitionSource to limit the number of open files
Merge pull request #1072 from aposwolsky/develop

Enforce invariant: mapGroup iterators all nonempty
bump scalding version to 0.12.0rc5
Refactor JDBCSource to add compile-time info about type of DB

- Turn drivers into traits
- Put all driver-specific logic in those traits
add vertica driver
Adds ability to also get the mode inside the Execution monad.
Merge pull request #1088 from CommBank/execution_mode

Adds ability to also get the mode inside the Execution monad.
change columns to def in ColumnDefiner
make all jdbc drivers traits
Add in failing test case
Change that passes all tests
Merge pull request #1090 from twitter/globifierBug

Add in failing test case
Adds a cumulative sum extension
Merge pull request #1085 from snoble/develop

Add a cumulative sum to KeyedList