fix(form-group): update margins & support static forms

CI had some issues without margin-bottom for .form-group.

This keeps the default .form-group margins and adds support for .form-horizontal-static to enable detail page type styles with form-group's. Might be a breaking change for people depending on this but it's nothing disastrous.
still a little bothered by the margin bottom on `.progress`. Went ahead and added the class back to this pr.

margins are in progress-bars.less:

```
// Outer container
.progress {
  overflow: hidden;
  height: @line-height-computed;
  margin-bottom: @line-height-computed;
```