UI improvements, new style etc

[romaninsh]

Merge #169 first.

Improves UI of Admin layout.

• Finally, ability to add top-right menu
• Layout is now responsive and will look OK on mobile and tablet devices
• Grids can be scrolled right/left if they have a lot of columns. They have their own scrollbar so they don't break rest of the UI. Grids also present info in a single column, unless it's a "text" column, which will try and trim your text.
• CRUD uses multi-column grid layout. This now puts appropriate spacing between fields and button.
• Using "Print" browser feature excludes menus, but should still have breadcrumb and content
• Added footer
• Ability to disable left menu entirely if you need more space

TODO:

• Reconnect the top menu. Currently it's static and will break apps.
• Add output caching and show them through alert in the toolbar.
• Rename *.jade into *.pug (inconistency)