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.
Fix Windows min/max animation on frameless windows

- Frameless windows disappeared or appears when minimized and maximized
on Windows. This commit fixes that.
Make sure frame is frameless
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
Merge branch 'master' into windows-min-max-animation
Fix code style to be <= 80 lines
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 #800 from frankhale/windows-min-max-animation

Fix Windows min/max animation on frameless windows
Merge pull request #801 from frankhale/http-referrer

Add http referrer to LoadUrl and Webview
Various fixes of #801
docs: "httpreferrer" attribute of <webview>
spec: "httpreferrer" attribute of <webview>