Bootstrap 3.2.0: register js needed for some components

Some components can be used without javascript function calls, only
by setting some html attributes or classes, allowing to use them
without writing specific BSL bindings.
E.g. `data-toggle="dropdown"`

Since there is no responsive css for bootstrap 3.2.0, use `import stdlib.themes.bootstrap.responsive` to register this js file instead of the responsive css. Otherwise, how can the bootstrap js be registered?
This should probably be renamed to a proper name, I was a bit lazy on it.