Features/bower dist optimisations

Hi Guy,

Here are just some tweaks to keep a single set of js/css files in the bower distribution.

So when someone does `bower install ng-cells`, he/she will get the following files:

```
project/bower_components/ng-cells:
|   .bower.json
|   bower.json
|   LICENSE
|
\---dist
    \---latest
            ng-cells.css
            ng-cells.js
            ng-cells.min.js
```

I also added a few folders to the .gitignore list.