fix(bsSwitch): `$apply already in progress`, default active state

The `$apply already in progress` error was due to the `bootstrap-switch` plugin changing the
`input` checked attribute _and_ manually triggering the `change` event; this seems to cause
angular to run two `$apply` calls, thus causing the error. Wrapping the initial `setState` in a
`$timeout` solved this.
Tests have been edited for handling both the new `$timeout` call (we have to wait for its
completion before testing) and the `input` use case (that seem to have a slighlty different
behavior).
The creation test has been enriched with some default values checking (active, strings, etc.).
Some minor changes have been made to the example page.

Fix #6 and close #7