IssuesController#create is no more scoped under project, but
IssuesController#new is, so we need to precise project_id
when redirecting to "New issue" form.

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@4083 e93f8b46-1217-0410-a6f0-8f06a7374b81