Fix Travis CI configuration

- Switch to Node-based builds
- Add Node 0.11 build
Refactor hook-related Given steps in JS stepdefs

*Push the how down!*
Refactor failing mapping JS step definition
Refactor failing mapping with message JS step definition
Refactor failing mapping JS stepdefs
Update README.md to correct error in example for zombie initialization

No zombie.Browser() object in zombie anymore..
So either do this (done in my patch):
this.browser = new zombie.Browser() ==> this.browser = new zombie()

Or do this (per the zombie examples):
var Browser = require('zombie');
...
this.browser = new Browser();
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Update minor typos in README.md

minor typos in the readme
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