Documentation about limitation in webpage.render

Closes #233
Refs #154
Fix: Shell wrapper "slimerjs" breaks if run in a whitespace containing dir

Closes #234
Fix tests about version
Add slimer.isExiting() to help script to stop their processing

Refs #237
Fix exception when webpage.close() is called twice at the same time

Refs #237
Doc: add a FAQ page
Fix tests for Gecko 33
Website - download page: specify supported/unsupported packages

Refs #244
Website: reorganized the features page.

Refs #254
Website: specify the gecko version on the home page

Refs #254
Fix: quality for webpage.render() should be between 0 and 100

To be conform with Phantomjs API
Closes #260
Fix compatibility with gecko33 in callPhantom implementation

Closes #249
Compatibility with Gecko 33 & 34 - package now include Gecko 33
Release of SlimerJS 0.9.4
website: information about checksum

Closes #245
Bumped version to 0.9.5pre
Merge branch 'v0.9'

Conflicts:
	docs/api/webpage.rst
	docs/conf.py
	src/application.ini
	test/initial-tests.js
	test/test-environment.js
	website/download.html