3.0 - Clean up Plugin and App classes

This change deletes a ton of now useless methods and features. The following things will die from this:

* `App::build()` now only handles view and locale paths. All class based packages should be setup through the autoloader of choice now.
* `Plugin::load()` no longer sets up an autoloader. Plugins will ideally be installed by composer, setup in the app's composer.json, or autoloaded by the developer.
* `App::location()` has been removed. It was pointless, as knowing a classname tells you where it is.
* The `file_map` cache file and features are no more.
* The core tests have had a pile of code expunged, this makes me happy.

#### New things

* Plugins no longer need to be 'loaded' unless you want those plugins to be part of the fallback routes, have them exposed to the framework or have their CLI tools exposed.

#### Some questionable changes that I'd like feedback on

* Plugin paths have been removed and replaced with a single default path. If you have plugins on alternate paths you need to explicitly define those paths when loading the plugins.


### Todo

* [ ] Figure out why the PluginTask tests are halting execution.