Added the ability to copy a project in the Project Administration panel.

Added the ability to copy a project in the Project Administration panel.

* Added Copy project button.
* Added Project#copy_from to duplicate a project to be modified and saved by the user
* Added a ProjectsController#copy based off the add method
** Used Project#copy_from to create a duplicate project in memory
* Implemented Project#copy to copy data for a project from another and save it.
** Members
** Project level queries
** Project custom fields
* Added a plugin hook for Project#copy.

  #1125  #1556  #886  #309

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@2704 e93f8b46-1217-0410-a6f0-8f06a7374b81