Add support for setting http referrer

- Add url option to specify the http referrer
- Add httpReferrer attribute to webview

NOTE: This is still not complete. Some love has to be done to
guest-view-manager.coffee and very likely the function calls called
createGuest and to the code that uses them.
Making Http Referrer addition better!

- Code cleanup
views: Make auto-hide-menu-bar work when NumLock is on, fixes #796
views: Fix showing menu bar when pressing Alt for a long time
Merge branch 'master' into http-referrer
Fix code style formatting

- Fix code style formatting to be <= 80 lines
- Add default parameter for urlOptions to loadUrl, reload and
reloadIgnoringCache functions to be compatible with old API.
Merge pull request #801 from frankhale/http-referrer

Add http referrer to LoadUrl and Webview