Add views for file deletion.

Hound strikes again.

Ajaxify directory creation The 'Create subdirectory' button now adds a line to the file browser containing a form. When this form is sent, an XHR is sent. If the directory could be created, the form is replaced by a link. Otherwise an error message is shown. The user can show as many forms as he wants.

split history action off of files controller

fix update file view

Refactor files action of FilesController Make use of RepositoryFile and GitFile. Use InheritedResources for FilesController and simplify files action (will be renamed later).

remove LimitsInitializer

introduce Commit class for history, lazy computing of deltas

hide edit button if file too large

fix file history pagination

finish #458

remove debug exception raising

move dirpath to helper

remove moved function

refactor files controller