Cleanup styles

[Refs #72712518]

Cleaned css a bit, moved styles from different themes into partials,
created variables partial.

Create home.css.scss

[Refs #72712518]

Updated home.css.scss, added imports.

Add metis-menu plugin

[Refs #72712518]

Update dashboard styles

[Refs #72712518]

Menu can be minimized now.

Add animate.css

[Refs #72712518]

Update sign_up/sign_in layouts

[Refs #72712518]

Styling sign_up/sign_in layouts, added animation to the form
(animate.css).

Update Welcome layout

[Refs #72712518]