add grunt task 'concat'

task 'concat' is for concatenating 2 files
- docs.css
- docs.min.css
change to load css files that are used only for github pages

This 2 files are concatenated into 'css/docs.all.css'
- css/docs.css
- css/docs.min.css
fix gh-pages auto deployment

add "bootstrap-multiselect" into "bower.json" as required package
tweak css of docs.css
update setup.sh

add "bootstrap-multiselect" as required packege
Merge pull request #20 from gengo/73270894buttons-dropdown

fix-auto-deployment