Add parseStatements to PlaceholderParser

And use that in the CPS transformers.

Fixes #523

Review URL: https://github.com/google/traceur-compiler/pull/536

Closes #536, closes #523.
Convert CodeLoader() to match ES6 Loader()
Isolate reporter and project in InternalCompiler
Rename ModuleRequireVisitor -> ModuleSpecifierVisitor
Bury project inside of InternalCompiler
bin/traceur.js to match