Upgraded Javascript

* Upgraded Template::Swig to version 0.13.5
* Upgraded Underscore.js to version 1.4.2

The the primary reason for these upgrades is to address a known issue
in which "extended" templates when compiled do not throw relevant
error messages. Now if there is a syntax problem it will report the
problematic line number.
Merge pull request #2 from logie17/master

Javascript upgrades to fix error messages with inherited modules.