This commit handles the conversion of:
* headers
* overviews
* warning_overviews
* controller/view debug output
* errors

Properly check for use of rails_xss gem

even if it's still a little broken in rescanning,
but how often will people be adding/removing rails_xss from their
Gemfile while rescanning?

Fix rescanning of deleted files

Stop alerting for Mass Assignment on `#update_attribute`

where it makes sense

Again, the check for this already exists, just need a test for it

check already exists, but no tests for it

fixes #78

Sexp#line can be used to retrieve or set the line number. No need to
invalidate the hash cache if line is not being set.

and also SQL injection duplicates in views, because that
is incidentally also fixed

when the mass assignment was actually in the controller

instead of losing it and causing all sorts of weird issues
and costing people sleep

although I don't think it makes a difference

Merge remote-tracking branch 'oreoshake/mass_ass_clobbering' into fix_mass_assignment_dupes_in_views

where it makes sense

Mass assignments were being clobbered, make api use consistent

Again, the check for this already exists, just need a test for it

check already exists, but no tests for it

Don't check find_by_* methods for sql