Chore/core removal

[runspired]

This PR removes modules not related to velocity usage. For the most part, this is a seamless removal

• Remove liquid-fire-core related modules
• Fix imports/exports in remaining files to use core if needed
• Supply animate function to liquid-fire-transitions

TODO:

• Amend Demo Site (Should the demos stay here, or in ember-animation/liquid-fire?
• Fix any tests that expected core / remove any tests that belong in core

Questions:

• Is registering an animate function with a specific API on the liquid-fire-transitions service the way to approach liquid-fire-core's need for an animate function within Growable
• Where does the velocity based demo site belong
• Do we remove explode (this is not velocity backed, so where does it belong?)