Author: Laurent David
MDL-75753 mod_bigbluebuttonbn: Support SHA256 and SHA512 checksum
* Add support for SHA256 and SHA512 checksum
http://git.moodle.org/gw?p=moodle.git;a=commit;h=7bd13d581de0290f9c1a23a064b0af54533194db
http://github.com/moodle/moodle/commit/7bd13d581de0290f9c1a23a064b0af54533194db
+ 4.2 en [config_checksum_algorithm,mod_bigbluebuttonbn]
+ 4.2 en [config_checksum_algorithm_description,mod_bigbluebuttonbn]