It seems like you have to interact with github.com to initiate a pull request. Is this so?
I've used this tool before- although it seems like there needs to be an issue open first, it is super useful and really streamlines workflow if you use github issue tracking. git open-pull and then a pull request is submitted from whatever branch you are on or select. https://github.com/jehiah/git-open-pull
EDIT: Looks like you can create issues on the fly, so this tool is a good solution.