New "page.loading" and "page.loadingProgress".

Now you can know about the Page Loading Progress
using 2 property:
- [bool] page.loading
- [int: 0-100] page.loadingProgress

Implements #1091: http://code.google.com/p/phantomjs/issues/detail?id=1091
Tests for the new "page.loading" property.

This commit provides the unit tests for the new property, as asked by
Ariya in #11091.
Importing new GhostDriver 1.0.3.

See the https://github.com/detro/ghostdriver/ project for details.
Merge pull request #11146 from detro/ghostdriver-dev

Importing GhostDriver v1.0.3