Adding CCDA generation to BB.js using EJS templating

The CCDA Generator can now successfully take several CCDAs that
pass the TTT, convert them to JSON, convert the JSON back to CCDA, and still pass.
That doesn't mean all of the data makes it through – some sections that BB.js
doesn't parse are left completely blank and other pieces of data that BB.js
supports are also left out of the template (like participants of a on a particular encounter)
because it makes it easier to produce a validating CCDA.

There is also a simple test for CCDA generation which
verifies that our expected CCDA json, fed into the generator,
consistently produces the same XML.

This builds off work by @kachok