Reduces the code duplication amongst the AMD, Browser, and Node tests,
to make it easier to keep them all up-to-date. As part of this, I am
including underscore in the test helpers, so that all three test runners
can use the _.each function
Adds C32 tests, using a sample C32 from
http://cda-validation.nist.gov/cda-validation/downloads.html.

This test doesn't make any normative judgments about how C32s ought to
parse / try to fix any potential bugs; it just captures the present
state of how we parse C32s, to prevent regression / support improvements
add instructions on how to run the tests to the readme
cleaning up a style issue