Added support for extra backends

Somebody had forgotten "OC_User::setupBackends();"...
Added support for extra backends (see pull request #5043)

Somebody had forgotten "OC_User::setupBackends();"...
Revert "Added support for extra backends (see pull request #5043)"

This reverts commit 2d75914f2a97cbfd34ae7c2ef27f5bd8185b81eb, reversing
changes made to 760fa9ea3005e7df81a1fac54f207dbe7d8ef312.
Add support mimetype

Add support mimetype for extension .sh, .bash and .sh-lib
don't specify path to 3rdparty directory when registering Pimple autoloader

The core 3rdparty directory is in the include_path from lib/base.php anyway, so this is unnecessary, and causes problems for downstream distributors who unbundle Pimple.
Merge pull request #6598 from lolozere/master

Add support mimetype
Merge pull request #6601 from AdamWill/pimple-include

don't specify path to 3rdparty directory when registering Pimple autoloader
Merge remote-tracking branch 'upstream/master'