Fixed 500 error with uninitialized helper method

Fixed 500 error with uninitialized helper method
Add delay on keyup and disable browser autocomplete on issue subject field.

Closes #60
Merge remote-tracking branch 'abahgat/master'

Conflicts:
	assets/javascripts/didyoumean.js
	init.rb
	lib/redmine_didyoumean/patches/search_issues_helper_patch.rb