Fix source maps with Traceur >= 0.0.72

Fixes #68. We now let Traceur generate its own source maps.

Adds a deprecation warning for traceurOverrides.sourceMap = true; Traceur now calls their option sourceMaps, plural.
Fix tests after Traceur upgrade

Two issues: Traceur now replaces all \s with /s in paths, causing tests to fail on Windows; and, Traceur has slightly different output for the code example.