Issue relation: fixes error with postgres when entering a non-numeric id...

Issue relation: fixes error with postgres when entering a non-numeric id (#4820) + accept hash (#) before id.

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@3413 e93f8b46-1217-0410-a6f0-8f06a7374b81