Adding dropup support to split buttons and navbar

* Documents the hidden .dropdown-menu.bottom-up option (to be used for dropups)
* Extends the .bottom-up class to carets and all relevant caret styles
* Adds .dropdown-menu.pull-right class for right-aligned dropdowns and dropups
* Adds examples and some information to the "split dropdown" and "navbar" sections of the Docs
Extending the dropup support to tabs and pills

This was needed to match the color of the carets that are used for tabs and pills
Fixing the Docs for Tabs dropups

New example caused an overflowing issue at the Tabs dropdowns documentation, this is a quick fix to get rid of this issue.
Clean up inverse button using variables, adding button group examples. Also adding inverse inline label
Adding .clearfix() to .form-actions to allow for .pull-right button containers
Keep origin in track
fix page header example and docs per #2048
fix grid typo in subnav
swap last .btn-dark reference
fix duplicate input prepend/append css selectors per #2026
removing duplicate reset filter since we changed the main button to use buttonBackground mixin, per #2024
add small section to navbar docs on text in the component, per #2035
add mention of js compilation to single file in customize page per #2003
fixed typo (whitespace)
fixed syntax error
Fixed a wrong behaviour when using collapse and dropdown in responsive layout
Fixed compile problem with LESS 1.2.1.

The sprite path variables introduced in v2.0.1 prevents bootstrap.less to
compile wiht LESS v1.2.1. Updated the variables to use the @{name}
construct when inserted in sprites.less, as outlined in the LESS
documentation. This change makes the CSS compile with LESS v1.2.1.
clarify misc components subhead
Merge pull request #2066 from artstorm/2.0.2-wip

Fixed compile problem with LESS 1.2.1.
clarify forms in navbar per #2072