Add support for Unicode escape sequences (\u{123})

Fixes #371
Partial sync up to changes in compat-table format.

Still a few cases which are incorrectly analyzed.

Review URL: https://api.github.com/repos/google/traceur-compiler/issues/1303

Closes #1303.
moved rsvp to dependencies
0.0.60
Commit binaries for 0.0.61