Add a commit message template

Using the `commit.template` setting, read in a commit message template
for each commit. This template is commented out so the commit message
author doesn't need to delete it.

The template serves as a reminder on how to write a better commit
message. The bullets are taken from Caleb's blog post[1]. There is no
_problem_ per se -- we are writing good messages these days -- but it's
handy to be reminded of things to think about. For example, people often
forget to note whether there are any side effects.

This message does not show on `git commit --amend`, only normal `git
commit`.

[1] http://bit.ly/13HWyiy
The user is able to type [ or ]

There are many workarounds[1] to the

    zsh: no matches found: ...

issue, but let's just stop it at its core: turn off that `nomatch`
functionality.

Apologies to all who enjoy seeing the pun around:

    % got a light?
    zsh: no matches found: light?

But all good shell puns[2] must come to an end.

[1] http://robots.thoughtbot.com/post/18129303042/how-to-use-arguments-in-a-rake-task
[2] http://www-users.cs.york.ac.uk/susan/joke/unix.htm
Merge branch 'master' of https://github.com/thoughtbot/dotfiles
updated i2 and aliases