Mattermost-plugin-github: Support for both github.com and enterprise server

[rien]

It is currently impossible to integrate two GitHub servers with the same plugin.

As a workaround: will stuff break if I edit the .tar.gz to just change plugin id?

[lieut-data]

@rien, with respect to the plugin id: if you change it everywhere you find it, it should "just work". Note that it's present in the plugin.json, as well as the server and webapp code.

Alternatively, if you rebuild the plugin from source you can just edit plugin.json and the framework should take care of effecting all the necessary changes.

(Leaving the issue open because of the larger request for supporting multiple servers.)

[sandeepsukhani]

Is it okay if I give this a try?

[jasonblais]

@sandlis Definitely, that would be great!

[sandeepsukhani]

@jasonblais Initiated a conversation here for design discussion.