Auto-populate the path and code on the name input's onchange event to the sluggified version of name

Project activities perfomance increased. Cache for project activitites disabled. Repository conception changed

2/ @commit.safe_message as an argument
3/ preserve in helper
4/ spaces around operators

It matches #[0-9]+ in commit messages.
For example
 * Fix for #12
 * Code review for #56
 * Test for #15, Review on #54, Fix for #42

 It only links to valid issues (existing and belonging to the current project)
 It does not add any link to the commit in the issue page, it only consists in parsing the commit message when displayed.

 This can be considere as a primary work for the issue #155 on gitlabhq/gitlabhq.