Support for CoffeeScript source files in combination with coffeeify

When a .coffee source file is run through transforms [coffeeify, debowerify],
debowerify can operate upon it just as it would upon a .js source file with no
problems. This is stopped by the guard clause at the start of the module,
however, which only lets .js files through.

Completely removing that guard clause might be reasonable; as far as I know,
browserify only ever looks at  source files of some kind or another, and if
users have dropped in the appropriate transforms (coffeeify, liveify, and so
on) there's no reason not to run debowerify on those non-.js files as well.
I've made only the minimal change needed to get my CoffeeScript-based project
working right, though---dropping the line entirely is worth consideration
nonetheless.
When a component's "main" is an array, use the first item in the array

`bower.json` defines the `main` option as (validly) being either a string or an array. debowerify previously assumed that `main` was always a string, so valid Bower components that chose to use an array instead would produce a `TypeError`. This patch has debowerify test the content of `main`, and if it's an array it will instead use the first element of the array.
Merge pull request #1 from 00Davo/coffee

Support for CoffeeScript source files in combination with coffeeify
coffee support and main array support via @00Davo
Merge pull request #2 from 00Davo/main-array

When a component's "main" is an array, use the first item in the array
main array support via 00Davo