Move inline properties to variables.less

moved buttons.less, carousel.less & close.less in this commit
moving code and dropdowns to variables.less
moving forms, labels and list-group to variables.less
Merge branch '3.0.0-wip' of https://github.com/saas786/bootstrap into saas786-3.0.0-wip
Update and add `@btn-hover-color` to Customize page
Update carousel vars

* Remove `@carousel-control-hover-color` since that's just the same as
the default control color and all we change is `opacity` (it's required
for specificity).
* Add vars to customizer
* Update customizer nav to include new section
* Remove the `li` from the var names
* Consolidate and simplify `text-shadow` vars
Update close vars

* Remove dupe hover color var (again, it's not necessary to have it's
own var here since we're controlling it via `opacity`)
* Add to customizer
Update code vars

* Drop the `rgba()` border and fallback because fuck that noise
* Add vars to customizer
* Remove rogue `:`
Update dropdown vars

* Update `.nav-divider` mixin to simplify to a 1px line (one value
instead of two in parametric mixin)
* Rename and consolidate dropdown caret vars
* Add vars to Customizer
Reorganize dropdown vars section
Update forms vars

* Reorganize layout
* Add input group var
* Add legend border var
Run make on prev commits
Merge branch '3.0.0-wip' of github.com:twitter/bootstrap into 3.0.0-wip