Update gems to latest keeping Rails on 3.2.x

fixes #11
Define base Shavar to handle chunk deletes
Add and Sub shavars inherit from Shavar
Ensure ChunkList can convert text lists to arrays
Define ChunkList to convert list strings to arrays
Response Helper delegates chunk deletion to models

and leans on the ChunkList to handle list conversions
instead of the ChunkHelper
Remove unused ChunkHelper#chunklist_to_sql