[Feature] implement --org for pull-request command

[blaggacao]

Although there is a more verbose syntax available via the head flag, in a standard use case where you want to do operations on behalf of an organization, the workflow is not really clean:

What we observe:

• If i did the pull with --org flag, the remote will not coincide with the github user
• If I do a standard hub pull-request, I do not get any helpful error message (no check is implemented if the user name remote exists)

What we would like to observe:

• Better checks and error messages
• --org flag for the pull-request command, so that the behavior get's consistent and we avoide the more verbose syntax.

I would even suggest to implement the --org flag top level on hub, so all operations get properly name spaced, if this would not conflict with upstream git.

[mislav]

Hi thanks for your suggestions. I still don't understand how the --org flag would work specifically. Could you provide examples, e.g. how a workflow would be done using current functionality with --head, and how would it look like with --org?