setup: Use find_packages() to find packages.

This makes gh-cli depends setuptools (or distribute).
But it's not a real problem because gh-cli already uses
`entry_point` to create script.
Basic implementation of gist.star and gist.unstar
gist: login befor starring and unstarring.
Fix gist.ls error on gist with non-ascii desc.
s/create.issue/issue.create/
remove issue.issues (has split)
Fix my command. (TODO: split)
Fix pull command (TODO: split)
help: show commands like gist
Fix some tests.
Fix more tests.
Fix tests.
gist.ls: Fix Python 3.2 support.
gist.ls: Use unicode_literals instead of ugly hack.
s/CreateIssueCommand/IssueCreateCommand/
Split issues command.
Add tox for easier test running