EXP-50. Fixes IllegalArgumentException bug in ScriptRunner.

Removes extra ',' added to the config entry "tmpjars".

Reviewed by: kiyan
EXP-23. Implement a Scala wrapper around KeyValueStores

This commit introduces the KijiExpress KeyValueStore, to be used
as part of the modeling SPI. A KijiExpress key-value store is a
Scala-friendly face on an existing KijiSchema key-value store, that
handles converting key/value types appropriately for users.