2.0.4 wip fix placeholder

adding the `&` combinator to `.placeholder` makes it work for the global case (in forms.less) as well as within `.navbar-search .search-query`

the result can be seen in the generated bootstrap.css, which include the -ms vendor extension.

fix navbar button for mobile tapping (turn to button instead of adding href=#), streamline less docs page

fix resizing issues from incorrectly changing <767px grid classes to inline-block, fix height issue on textareas