Added list builder to build list of sources.

- will go into the Rakefile refactoring
- Builder takes a source and a bunch of filters
- and returns a list of files.
- filters take an input and expand it into and array which
  gets concatenated into the final result.
- DirExpander - expands dir to files for pattern
- FileContentFilter - includes or excludes files based on pattern inside their content.
- PatternFilter - filters on filename
- ExtensionTransform - converts file extension
- AbsolutePathTransformer - converts to absolute file paths
Refactored Rakefile.

- TEST_SOURCES and TEST_COMPILED now just accepts a filelist
  does not do any globbing of its own, the globbing logic
  has moved to Speckle::List.
- Eventually will not need this at all if we use Riml's compiler
  directly instead of 'sh bundle exec riml'
- Moved RakeApp initialization into the controller.
  should speed things up for code paths that don't use the rake_app.
Merge branch 'feature/custom_filelist_builder' into develop