refactor to a plugin

@ianstormtaylor this move the plugin out of integrations to here. all the tests are updated and passing (we removed a bunch of them because the are no longer needed since we are just using `analytics.track` and such now, on a regular integration).

we can merge this now and because duo allows using two different versions of the same component, we can use both 1.0.0 and this plugin version (1.3.0) in the same project.

ready to merge whenever you guys are good with it!

/cc @yields