Add ClassCheck preference and disable StringLiteralsInInterpolation cops

[skip ci]
Remove "initialize" method from StorageManager model.

The initialize method of the StorageManager model class was calling super()
and in so doing, not passing the proper args to the subclass. Given
this was all the method did, the entire method has been removed.

https://bugzilla.redhat.com/show_bug.cgi?id=1171286
https://bugzilla.redhat.com/show_bug.cgi?id=1171899
revert sass gem to 3.1.20
Issue: #1200
Merge pull request #1202 from epwinchell/revert_sass_gem2

revert sass gem to 3.1.20
Fix session store on metric_fu environment
Merge pull request #1195 from roliveri/storage_manager

Remove "initialize" method from StorageManager model.
Merge pull request #1203 from Fryguy/fix_session_store_on_metrics

Fix session store on metric_fu environment
explicitly cast column types when migrating

PG doesn't support implicit casting anymore because it could incur data
loss.  This explicitly casts data types using the API in upstream Rails.

This depends on manageiq/rails#15
Bump to rails fork containing support for casting.

connection.change_column :strings, :somedate, :timestamp, cast_as: :timestamp
connection.change_column :strings, :somedate, :timestamp, using: 'CAST("somedate" AS timestamp)'
remove `virtual_columns=`

this reduces the surface area of the virtual colums api, and will make
it easier to port to Rails 4
remove `virtual_reflections=`

We are not using this method in the application, and removing it will
ease porting virtual columns and reflections to Rails 4
Merge pull request #1156 from tenderlove/explicit_cast

explicitly cast column types when migrating
Merge pull request #1194 from Fryguy/update_rubocop_warning_list

Add ClassCheck preference and disable StringLiteralsInInterpolation cops
Merge pull request #1174 from tenderlove/virtual_assignments

Remove virtual assignment methods