Support for Bluemix DevOps Git service

[uetchy]

Thank you for making great tool!
I created support for Bluemix DevOps service.
Bluemix only supporting HTTPS so we need to show prompt.

[motemen]

Thanks! Built-in support for hub.jazz.net seems good, as seeing go get also supports it.

But why we have to GIT_TERMINAL_PROMPT to 1? I don't get the point why we'll need to do it.

[uetchy]

Unfortunately, Bluemix is only available on HTTPS so we need to show prompt for username and password to authentication. But there is chance of be suppressed to ask users with GIT_TERMINAL_PROMPT=0. Actually in my situation, prompting any messages was disabled by this env var. To assure to ask users, we need to set GIT_TERMINAL_PROMPT to 1 (I know this is not the best idea).

[motemen]

Thank you, I see.

But as the default value of GIT_TERMINAL_PROMPT is nonzero, the user should have set it to zero somewhere. So as a thin wrapper of git, I don't think ghq has to support this environment variable, rather it's the user's responsibility to set the environment variable to nonzero. How about that?

[uetchy]

Yeah I changed the mind; there are splittable problem. I removed all changes to vcs.go first.
I will send PR later If I can fix the prompting problem.
Can you merge them?

[motemen]

LGTM, thanks!