Interpret modules

 Command line interpret mode adapted for import().

    Given a filename, convert it to a normalized module name.
    Clean up some leftover code.

Review URL: https://github.com/google/traceur-compiler/pull/656

Closes #656.
Resolve only names beginning with dot against referrerName

Review URL: https://github.com/google/traceur-compiler/pull/665

Closes #665.