Remove gravatar and no-avatar functionality, prepare for default avatars even more and reword some stuff

- Don't use gravatars default avatars
- Use "profile image" instead of "avatar"
- Use <p> instead of tables
- Ease updateAvatar()
- Actually return something in \OCP\Avatar

TODO: Fix OC_Image->mimetype(), it always returns "image/png"

And other small improvements

Improve app-management

Do not use realpath() on includes.

Conflicts:
	settings/js/apps.js

This is possible because we require PHP 5.3 or higher.

If the file does not exist, realpath() returns false and "include false;"
produces "Failed opening '' for inclusion" which is a useless error message.

'include' works just fine with symlinks, "./" and "../".

Fix some JSLint warnings

Use JSON to send/receive group data.

use strict equals in readdir loops to prevent issues with '0' files

Fix files_external webdav up and download when path contains ' '

Move quota logic from filesystem proxy to storage wrapper

adding file templates for ods, odt and odp