Allow components (other than brand and toggle) to exist outside collapse within navbars

[jokokoloko]

Chrome on Mac. Comparisons between WIP and RC1.

Please allow components (specifically a right-aligned dropdown menu) to exist outside of the collapse within navbars.

With this it is relatively easy to create the common 3 component (toggle, brand, [random component]) navbar layout that seems to be popular in many mobile sites and applications. This was very easy to do in RC1 and required only a minimal amount of additional styling but attempting this in the WIP version is quite a mess, especially with the navbar-header requirement.

Here are jsFiddle examples of this layout:

RC1: http://jsfiddle.net/jokokoloko/t4ww3/
WIP: http://jsfiddle.net/jokokoloko/ZmxQp/

Some quick screenshots:

RC1

WIP

[mdo]

We won't be doing this for v3, but I'd be open to tweaking this to account for this for v3.1 as long as we don't break backward compatibility. I'll track it via #9397 for 3.1.

[jokokoloko]

Sounds good :) Thanks!

Also, the ability to easily switch alignment of the brand (navbar-brand-center, etc.) and toggle (navbar-toggle-left, navbar-toggle-right, etc.) within the navbar would be a nice bonus ;)