Add after_index and after_remove callback options
Update templates to use auto_index and auto_remove
Add database_cleaner and clean using transactions
Use index/remove after_commit
Fix deprecation warning mock -> double
Remove extra line in spec_helper
Add auto_*_callback docs

Requested as per https://github.com/sunspot/sunspot/pull/532
Merge commit '266cdf69d8fdf486b98c8c6cd601ccdaaf79fefd'