Show people what's going on and how to use the extension.

* Description
* Installation notes
* License information

MIT license.

Apparently Wikipedia uses `input[type="search"]`. Might as well include
it since that's probably a common type of input for this use case.

Move the key code numerical values into a hash so we can refer to them
by name instead of obtuse magic numbers.

This was used to test out simulating a down arrow key press on the
Google search home page with the field selected and something typed in.
If the first entry in the suggestion drop-down was selected after the
timeout fired, that means it worked.

We no longer need this test code.

Instead of handling the keyboard events in the content script, inject a
script onto the page that does the key listening and simulating.

This allows the simulation of up & down arrow key presses to actually
trigger the proper page event listeners and allow our custom code to do
the right thing instead of firing a key event in the Chrome extension's
isolated environment and not having anything happening because no
listeners are attached in the isolated environment.

Also inject the `KeyEvent` object from Mousetrap so we can use it's key
simulation feature. Will likely want to extract that into our own custom
code so we're not including a whole script that we only use 20% of or
so.

Doesn't quite work. We're correctly listening for Ctrl-N/P presses, and
seemingly correctly simulating corresponding up/down key presses, but it
seems that the 'content scripts' can't trigger page events.

See
https://developer.chrome.com/extensions/content_scripts#execution-environment
which describes the "isolated" execution environment of Chrome content
scripts.

Spent a while trying to figure out why this wasn't working. Finally
looked back through my Chrome console history and found out what I did
previously to get it working and it turns out that was the same thing
I'm doing here. Finally had a moment of inspiration that prompted me to
look into the different execution environment thing.

Found a useful Stack Overflow post that descibes how to inject a script
onto the page, which will give me access to the page's context:
http://stackoverflow.com/questions/9515704/building-a-chrome-extension-inject-code-in-a-page-using-a-content-script

Doing that should get this working, so that's what I'm going to try
next.

Work in progress.

Get all inputs on the page. Bind a callback to their focus event. The
intention is that when the input is focused, I attach a handler to
listen for Ctrl-N/P presses.

Now that I'm writing this and thinking about it though, I might as well
just bind the Ctrl-N/P listeners to all inputs to begin with an be done
with it. Kind of a brute-force way of dealing with it but then I
wouldn't have to keep track of whether or not I've bound those listeners
to an input that was already focused previously.

* Create limited bower.json file
* Create .bowerrc that tells Bower to use the `lib` directory
* Install Mousetrap for key events