Add new login screen

Hide login screen elements depending on the enabled auth systems.
Refactor LoginAction for readability.

Override default login error message.
Modify Credentials screen to use the same styles as the new login screen.

Refactor OpenId authentication method on AuthenticationManager.
Merge remote-tracking branch 'origin/integration/master' into new-openid-login-screen

Conflicts:
	pom.xml
Fix wrong expression in pages.xml
Rearrange tab index for login screen.

1. Username field
2. Password field
3. Forgot password link
Merge pull request #173 from zanata/new-openid-login-screen

New openid login screen