RFE: allow use of different authentications systems than github.com for corporative use

[abmpicoli]

For corporative use, it would be nice to have a dedicated teletype server , that points to a different authentication system. For example, even github can be github.the.corporation.com , instead of github.com .

[jasonrudolph]

For example, even github can be github.the.corporation.com , instead of github.com .

For anyone wanting to authenticate with their GitHub Enterprise instance, #36 added support for running a teletype-server instance that authenticates with your company's GitHub Enterprise instance.