Author: Laurent David
MDL-76710 mod_bigbluebuttonbn: Subplugin implementation
* Setup the base for extension type of plugins
* Add basic unit test for extension plugin (callback and classes)
http://git.moodle.org/gw?p=moodle.git;a=commit;h=dfeedc5dabfcca995a059a1105ca3cd2acf8c243
http://github.com/moodle/moodle/commit/dfeedc5dabfcca995a059a1105ca3cd2acf8c243
+ 4.3 en [managebbbextplugins,mod_bigbluebuttonbn]
+ 4.3 en [subplugintype_bbbext,mod_bigbluebuttonbn]
+ 4.3 en [subplugintype_bbbext_plural,mod_bigbluebuttonbn]