Fix glyphicon in "Dropdown in a button group" example

Fix caret position

Fix

Couple of fixes for docs and examples

* Remove border-radii on top of tab dropdown menus
* Remove the .dropdown and .dropup styles and instead place  on all
* Use  on dropdown carets intead of separately applying margin with a top alignment
* Some other misc cleanup

[v3] Fix the selectors for the .input-group-btn class

Remove the overrides and resets from button groups

* Use 1.428 for line-height instead of 1.5
* Use  function for full pixel values instead of decimals

Fix component margin and padding values to use @line-height-computed

Fix link to examples