The Horizon login page was not properly inheriting its styles from
its theme. The implementation was making use of the _modal_form.html
template just to inherit a form, but there was no way to remove
the modal classes with that implementation.
The login page now uses a standard Bootstrap 'panel'. This will
inherit the look and feel of any theme more naturally when its not
inside of a modal, as not all themes use box-shadow outside of a
modal; some chose to be very flat on purpose, and the built in
panels take advantage of this.
When used within the Region selector, it does need to exist within
a modal, so some simple logic was added for the classes necessary.
The panel is a little bit wider than it was before, but it is now
a standard Bootstrap column size, so its responsive down to a very
small screen size.
The modal is a little bit wider than it was before as well, as it is
is now the standard medium modal size for Bootstrap.
Improvements:
* Logo is now an <img> tag, which means it can automagically resize
to fit in the available space
* Unneccesary styles removed
* _splash.scss was only being used in _login.html, which was
confusing, so _splash.scss is renamed to _login.scss, and is now a
class based style, so it can live in /components
* Its now Theme ready and responsive
* Region Selector Login now has a proper modal backdrop
* has-error help-text should not be alert alert-danger
Partially-Implements: blueprint horizon-theme-css-reorg
Partially-Implements: blueprint bootstrap-html-standards
Change-Id: Ie968414ab8ef2154623edfc21ce5623e8c4057c6