adds .button-primary to *Add row/group* button
tabs to spaces for better alignment
makes regular-text field 100% width in postbox, bg-color for group title

also improves borders display a little
generated css
slightly different group-title margins for postbox and other places
converts add-row link to button (<a> -> <button>)
Merge branch 'master' into styling
limit repeatable row table display to postbox container
changed first-child -> first-of-type, last-child -> last-of-type, see #33
Merge branch 'master' of https://github.com/WebDevStudios/CMB2 into styling
Merge branch 'styling' of https://github.com/senicar/CMB2 into senicar-styling

Conflicts:
	includes/CMB2_Types.php
Don't use button-primary.. it's gratuitous and is not a 'primary' thing.
Make table-layout class that applies to text_url and text types when repeatable. Also make types filterable and row classes filterable
Merge branch 'senicar-styling'. Props @senicar.
Merge branch 'master' of github.com:WebDevStudios/CMB2