fix for 0004589: Administrator cannot manage projects to which he/she is assigned.

• removed project assignment from page when user is an administrator
• fixed access check to use global administrator as an override

git-svn-id: http://mantisbt.svn.sourceforge.net/svnroot/mantisbt/trunk@3417 <a class="text" href="/?p=mantisbt.git;a=object;h=f5dc347c">f5dc347c</a>-c33d-0410-90a0-b07cc1902cb9