No way to push newly created branches #243

If the user creates a new branch in the Git Panel, the Push/Pull view disappears because there is no remote tracking branch.

Possible solution: Display Push and Track button that pushes and sets up the remote tracking. Or should we honor the user's git config settings in the case that they don't have automatic remote tracking enabled and prompt them to ask them if they want to create a one.

Also we should handle the case of pushing a newly created branch that has the same name as an existing remote branch.