Merge pull request #11 from sirodoht/master

Added Greek locale
Added gold medal for hunter2 cheevo
Adjusted bar for achieving the gold Split Personalities
using the userstyles module
adding a test for stylesheets
adding a test for 'about:cheevos'
updating the way that the toolbar button is updated
Merge pull request #13 from erikvold/issue-12

using the userstyles module
Merge pull request #14 from erikvold/issue-14

adding a test for about:cheevos
Merge pull request #15 from erikvold/issue-15

Updating the way that toolbar buttons are updated
using internal sdk code for pref observer
adding unload handler, reusing some code, using isBrowser helper, more
removing unused variable
removing unused line
separating the window tracker code from constructor
Merge pull request #17 from erikvold/preftarget

using internal sdk code for pref observer
Merge pull request #18 from erikvold/ao-update

achievement-overlay module updates
Updated to use the SDK v1.14
Now using new Private Browsing APIs
Don't award achievements for page visits if the visit is inside of a private window.