Cleanups

[balloob]

Just some cleanups around app startup.

Also making LitElement's css available on the prototype. (CC @thomasloven @bramkragten )

[iantrich]

I'm not too familiar with exposing things on prototype, but can anything be exposed in this way? e.g. could we expose the navigate functionality to custom cards?

[balloob]

@iantrich for navigation, just use <a href="/lovelace/something">BLA</a>, our navigation code will intercept it

[balloob]

I don't like to expose internals, but as people were extending our elements, without the proper css and html there is no possibility to create your own templates.