Generalizes image upload in drag and drop in markdown to all files

From https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/265 by Hannes Rosenögger.

- [x] Rebase on master when !1553 is merged in

See merge request !1530

Conflicts:
	app/views/import/gitorious/status.html.haml
	db/schema.rb

Bump gemnasium service gem

# Conflicts:
#	app/controllers/files_controller.rb

UI: refactor header css

See merge request !1591

Improve admin projects and users pages for mobile devices

See merge request !1590

Give last_activity_at a default value so it will always be set

For https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/345

See merge request !1589

Fix 404 when deleting a project from the admin section

This is some additional fallout from the rails upgrade. Need to use plural namespaces in the path function to get project deletion to go back to the project listing.

See merge request !351

Updated Gitorious import icons

See merge request !353

Improve contributed project and commit calendar selection.

Fixes #2024.

See merge request !1554

Update gitlab-grack to 2.0.0.rc2

See merge request !1585

Toggle sidebar button more obvious

The toggle is now at the top of the sidebar because it is not noticeable
near the bottom. By placing it at the top, users will immediately know that
they can have more space if they desire versus on the bottom, they will have
to search for it and that's not desired.

Fixes #2044

See merge request !1579

Conflicts:
	Gemfile.lock

This reverts commit c217860a.

Update gitlab-linguist

Closes #1859

See merge request !1588

Web Editor: save to new branch

Implements #1931

See merge request !1523

This was done to show difference between Open/Close toggle, which
was using the same arrow as Back to Settings button previously.

access