Removed dependency

Concat is no longer required since browserify is doing it for us.
Deleted bootstrap LESS files

We are going to be pulling in bootstrap using npm so we don’t need
these static files anymore.
Deleted CSS created by tasks

Just to remove the change of out of date code creeping in. These files
are generated by the grunt tasks anyway.
Update .gitignore

Now ignoring generated css and bootstrap.
Bootstrap now being deployed during build

NPM will install the latest bootstrap for us. Grunt then copies the
files over for us (which are used by our main.less file) and also
removes css/_vendor/bootstrap/variables.less so that we can override it
with our custom version.