This allows autoconfig files to use 'dbpassword' instead of 'dbpass', which
is more consistent with config.php

* Avatar for "xxxx share with you..." to the left
* Avatars for groups and remote shares (use default placeholder)
* Modified and added unit tests
* Use the same css for all the avatars in the dropdown

Doing this in the PHP code is not the right approach for multiple reasons:

1. A bug in the PHP code prevents them from being added to the response.
2. They are only added when something is served via PHP and not in other cases (that makes for example the newest IE UXSS which is not yet patched by Microsoft exploitable on ownCloud)
3. Some headers such as the Strict-Transport-Security might require custom modifications by administrators. This was not possible before and lead to buggy situations.

This pull request moves those headers out of the PHP code and adds a security check to the admin settings performed via JS.

Otherwise problems arrive when a username contains characters such as an `@`

Fixes https://github.com/owncloud/user_shibboleth/issues/38

This reverts commit 6a1a4880.

**Changes:**

* In line 103, the middle "c" of "owncloud" is capitalised to "ownCloud".
* A space is inserted between value and unit in lines 177 and 187 ("4 GB" instead of "4GB").