New pull with all of my commits so far

This pull request includes dealing with issue https://github.com/Goles/Battery/issues/7, with the '-p' option, merging ivanvc/master https://github.com/ivanvc/Battery/commit/47f6dad276c2455280413254deb6bbc47d00d90a (lightning for when charging), creaktive/master https://github.com/Goles/Battery/pull/10 (more concise ioreg), and https://github.com/Goles/Battery/pull/12, which I accidentally closed when deleting my 'pmset' branch. The '-o tmux' flag has also been replaced with '-t' in #12, seeing as there aren't any other output formats.

If you have any concerns before merging please let me know.

Cheers :)