Driver can enable or disable PhantomJS cookies

As of 1.7, PhantomJS allows its `CookieJar` to be enabled or disabled using the
`cookiesEnabled` function. This commit adds access to that from the driver
using a similarly named `cookies_enabled=` method.

For more information on the API, check out:

https://github.com/ariya/phantomjs/wiki/API-Reference-phantom#cookiesenabled-boolean
Merge pull request #300 from mfrost/cookies_enabled

Driver can enable or disable PhantomJS cookies
Improve PhantomJS version checking

Naive implementation of raw string comparison fails on version
starting from '1.10.0'. The new implementation converts version parts
to integers and checks them in turn starting from major part.
Merge pull request #318 from hron/improve-phantomjs-version-checking

Improve PhantomJS version checking
Can set cookies for given domain