Add Moodle 2.3 addinstance capability

[andrewnicols]

Moodle 2.3 introduces the addinstance capability.
I've taken the liberty of also incrementing the version, and adding a dependency for the recordings plugin on the bigbluebutton plugin.

[jfederico]

Hi Andrew, thanks for the post but we already have that implemented. This and some other fixes for the auto-testing.

We also move the project to https://github.com/blindsidenetworks/moodle-mod_bigbluebuttonbn, the latest version is right there. This repo is going to be depreciated soon.

Thanks again

[ffdixon]

Hi Andrew,

A BIG thanks for sending this pull request. As Jesus said, we've been working on updating the BigBlueButton BN integration for Moodle 2.3 and will be putting up a new version. It would be great if you could try out the newer version when it's public and let us know if you find any problems.