Upgrade Commoner and Recast to latest versions.

The Commoner upgrade is a big one because it makes bin/jsx no longer
rewrite module identifiers to be relative by default, which should
reduce confusion for people trying to use it as a standalone
transformer.

Closes #80.
Merge pull request #81 from benjamn/issue-80-commoner-no-longer-rewrites-require

Upgrade Commoner and Recast to latest versions