To get repo language is not necessary for none github.com repository

[linux-china]

If you use Sail to run project on your internal git hosting, for example:

sail run gitlab.xxx.com/user/repo1 

and Sail still call "get repo languages api" and generate 404 not found error.

2019-05-23 13:29:50 ERROR	unable to get repo language: GET https://api.github.com/repos/user/repo1: 404 Not Found []
2019-05-23 13:29:50 INFO	using default image codercom/ubuntu-dev
2019-05-23 13:29:50 INFO	ensuring image codercom/ubuntu-dev exists

Please remove repo language REST API call for none github.com project.

[teddy-codes]

This is only done when there is no .sail/Dockerfile within the cloned repo since at that point, it tried to guess.

[deansheather]

Closing in favor of #197.