NG-1666 Try to parallelize JavaScript builds
NG-16666 Add logging for thread count
Minor fixes
Add more logging
Add a check for the steal.js directory that aborts if it does not exist
NG-16666 Try setting a maximum of 4 concurrent builds
NG-16666 Trying raising maximum threads to 8
NG-16666 Add max-threads command line option
NG-16666 Upgrade to Rhino 1.7R4
Revert "NG-16666 Upgrade to Rhino 1.7R4"

This reverts commit 88cb97d75b5fa5e557a82d30e45ea04317a1be0e.