Allow active jobs to adapt to structural changes to the data

[GoogleCodeExporter]

Current, attaching feeds to datasets prevents structural changes (e.g. creating 
an index) from occurring to the attached datasets. 

Especially with the addition of other types of active jobs, we need active jobs 
to account for and allow these potential changes.

Original issue reported on code.google.com by sjaco...@ucr.edu on 10 Aug 2015 at 5:37