Fixes an issue where failed jobs re-run repeatedly
Check for MassAssignmentSecurity constant when deciding to set attr_accessible

ActiveRecord 4 *may* require setting attr_accessible if the 'protected_attributes' gem is installed. This changes checks for that case.
Update active_record.rb
Tests for protected_attributes and rails 4
Merge remote-tracking branch 'origin/pr/53'

Conflicts:
	lib/delayed/backend/active_record.rb
Prep for release 4.0.0.beta3
Add gem release tasks to rake
Adding support for the Teradata adapter, which needs the same behavior as the MSSQL adapter
Add missing require statement to load ActiveRecord generators
Merge remote-tracking branch 'origin/pr/67'
Prep for 4.0.0 release

[ci-skip]
Don't build against 1.8 anymore

[ci skip]
Added support for singleton queues
Don't use root DB user
Small fixes
Add singleton queue specs
Clean up query and add additional comments
Clean up singleton specs
One more spec tweak
Move SQL to single line to avoid messy logging