[API] Implement register/unregister global desktop keyboard shortcut on Winodws.

- Introduce GlobalShortcutListener;
- New api object: Shortcut({'key': '...', 'active': ..., 'failed': ...});
- New api: App.registerGlobalHotkey, App.unregisterGlobalHotkey.
[Test] Manual test case for global keyboard shortcut.
[API] Finish register global desktop keyboard shortcut on linux.
[Test] Automatic test case for keyboard shortcut.
Remove DCHECK limitation of GlobalShortcutListener.
[API] Finish register global desktop keyboard shortcut on OSX.
Improvement: |key| of |Shortcut| should be case-insensitive.
Address comment: change {un}registerGlobalHotKey to sync method.
Fix build error of missing parameter: isolate.
X11ErrorTracker has been moved "ui/gfx/x/".
Fixes typo.
Check URL before navigation

Fixed an error when an invalid url is given in the address bar.
Append http proxy auth test case.
Merge pull request #2047 from davidgomes/patch-1

Fixes typo.
Merge pull request #2054 from gitchs/http-proxy-auth

Append http proxy auth dialog test case
Merge pull request #1735 from zhchbin/hotkey

[API] Implement register/unregister global desktop keyboard shortcut.
Update CHANGELOG.md

Fix #1984
[OSX] Fix #1996: resize with flash on 10.9

This is upstream bug #385120
Merge pull request #2044 from libm/master

Check URL before navigation
Fix should.js usage error