purge cache only once on install

this is not a extension specific cache but a global one. no need to
purge for each installed extension

check for admin in AJAX backend

treat non-existing files as success on delete

now use new core funtion to recursively delete

added tests for io_rmdir

added recursive delete function to io.php

added status to info list of extension plugin

added css and html changes for RTL scripts to extension manager

added basic mobile styles to extension manager (not great, but makes things at least readable)

fixed and improved some HTML in extension manager

added git warning

fixed strict standard error and added some docblock

removed the old plugin manager

typo fix

protect authplain and current auth plugin

do not show updates for bundled plugins

protect extension, not plugin anymore

use config for firguring out if an extension is protected

even more fixes for the bundled extension list

template:default is no longer bundled

the plugin is called testing not test

fixed error in .travis.yml

AUTH_ACL_CHECK event around ACL checking

allows to modify ACL results in the AFTER event or to implement a
completely different ACL mechanism in the BEFORE event.

notify IRC on change only

also notify IRC channel