admin-ui: Initial clean up of navigation sass
admin-ui: Clean up extra.scss
admin-ui: Refactor sass files

Fix apyrgio/synnefo#96

Two main css files are included in base.html:
bootstrap.css and global.css
Both of them import settings.scss that holds all our app settings
and bootstrap variables.
admin-ui: Minor js fixes
Merge branch 'feature-admin-fixes' into feature-admin