Fix AssetCompiler tests.

I needed to camelize the theme name as without that we'll constantly run
into issues where plugins "don't exist" even though they do.
Get helper tests passing again.

Account for a few things:

* Cache throws exceptions on missing cache configs now.
* Helpers have a config() method that does different things now.
* webroot moved around.
* Router::fullBaseUrl() always exists.
* HtmlHelper::css() changed.
* Default HTML templates are different.
Remove redundant code.
Fix more failing tests and incorrect class imports.
Fix remaining failing tests.

This might be the *wrong* fix as it requires fully namespaced
classnames, for settings to work. This might be a pain in the config
file, and need to use just the class without the namespace instead.