This commit will make the supported DBs for installation configurable within config.php. By default the following databases are tested: "sqlite", "mysql", "pgsql". The reason behind this is that there might be instances where we want to prevent SQLite to be used by mistake.

To test this play around with the new configuration parameter "supportedDatabases".

Otherwise the function is executed n times which is a lot of overhead

There is not much sense in having these files marked executable, we should avoid that.

* fix #7484
* use UID, css, and div instead of span

Actually query() returns value of the type "mixed" (as is also stated in the interface) - this is purely there to make our IDEs and Scrutinizer happier.

Remove \OC\DB\ConnectionWrapper, have \OC\DB\Connection implement \OCP\IDBConnection directly instead

There is no need to refer to the absolute path here if we can use the relative one.

Conflicts:
	lib/private/templatelayout.php

suspend encryption proxy when copying skeleton