Updating build dependencies

Hello everyone,

This pull request is just for discussion _(for now at least)_. As far as I see, build dependencies is out of date and I've tried to update them to latest.

I make this changes:

1. `node-markdown` was deprecated, I've used `marked` instead of it. As suggested [here](https://github.com/andris9/node-markdown).
2. Removed `jenkins` configuration of `karma` since I haven't seen where it is used and unable to test it.
3. Updatad `karma.conf` to new config structure.
4. Updated `gruntfile.js` to work with [this](http://gruntjs.com/blog/2013-11-21-grunt-0.4.2-released) changes.

As far as I see it works. But I am not sure. I must have missed something.

Also, I've some questions:

1. I haven't seen how output of `grunt ngdocs` is used right now. It generates some kind of a documentation but it not the one we see at `gh-pages` branch. I didn't get what it is.
2. How `gh-pages` is generated? Is it an grunt automated process?