Fixed enumerations save bug

Due date was not being correctly updated when changing the SLA seconds
field in the priorities page under enumerations. This is now fixed.
Also moved some methods into a helper module.
Merge branch 'master' of https://github.com/dannybutler/redmine into dannybutler-master
Accidentally removed method

Adding notify_change back in.
Merge branch 'dannybutler-master'

Conflicts:
	src/plugins/aam_sla/lib/issue_priority_patch.rb
Merge branch 'master' of https://github.com/dannybutler/redmine
Merge branch 'master' of https://github.com/artsalliancemedia/redmine