BBB should only include core libraries as required

There are a lot of libraries being included in lib.php which means they are included everywhere throughout Moodle, even when they are not required:

https://github.com/blindsidenetworks/moodle-mod_bigbluebuttonbn/blob/50b31b851b645eb167b0c4958dc601decc02fc50/lib.php#L31-L40

It would be better to re-factor BBB's own library code to only require these libraries when necessary