Signed-off-by: NDmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

- Offloads uploading to GitLab Workhorse
- Use /authorize request for fast uploading
- Added backup recipes for artifacts
- Support download acceleration using X-Sendfile

This reverts commit 7d5f86f6.

This commit generalizes the image upload via drag and drop so it supports all files.
It also adds access control for these files.

This commit moves the note folder from
/public/uploads/note
to
/uploads/note
and changes the uploader accordingly.
Now it's no longer possible to avoid the access control by modifing the url.
The Avatar upload has been refactored to use an own uploader as well
to cleanly seperate the two upload types.

This reverts commit b37b71d8, reversing
changes made to 42a1d808.

The attachment URL was not working with relative_url_root not equal to '/'. I suggest this fix.

Ref: https://github.com/gitlabhq/gitlabhq/commit/e6159b8725f99af78f446f8d33fa0e52b7780430
Ref: https://github.com/gitlabhq/gitlabhq/pull/3204
Ref: https://github.com/gitlabhq/gitlabhq/issues/1228

Add Rails' variable in application.rb to support relative url

This variable is used by assets compilation and other modules.

Note that user needs to change application.rb too

Restrict session cookie to the relative path if set.

Ref: https://github.com/gitlabhq/gitlabhq/commit/2c2f1e31856a4decdae469974f5bea8245316f7e

Fix Update attachment_uploader.rb bug with relative URL

See: https://github.com/gitlabhq/gitlabhq/commit/161afda3fa4fca58f396e9c3acbd72bc14490ace

Fix Wall relative bug with attachement files (javascript)

when showing image preview check via lowercased extension and adds support for gif bmp & tiff images

Didn't bother with files in db/, config/, or features/