Bug 25549: Remove plugin methods for broken plugins

Bug 25549: Remove plugin methods for broken plugins

To test:
 1 - Enable plugins in the koha-conf
 2 - Install the kitchen sink plugin
 3 - Your staff client should be orange now :-)
 4 - edit the plugin module
     /var/lib/koha/kohadev/plugins/Koha/Plugin/Com/ByWaterSolutions/KitchenSink.pm
 5 - Add a line to break compilation, like:
     this won't compile
 6 - Restart all
 7 - Your koha is now broken
 8 - kshell
 9 - perl misc/devel/install_plugins.pl
10 - Restart all
11 - Koha remains broken
12 - Apply patch
13 - kshell
14 - perl misc/devel/install_plugins.pl
15 - Koha now works!
16 - Koha is not orange because the plugin methods are removed

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>