Support for removing call groups of namespace

Hi!

In @Solpeo Game Engine we use simple BDD style assertions like [should.js](https://github.com/visionmedia/should.js/) in a code.

This pull request add new functionality into namespaces support: all call expressions sticks to the namespace will be removed.

**Example:**
If we want to remove `debug` namespace the whole `debug.expect(true).toBe(true)` expression will be removed.