corrected ref of env variables from _INSTALL_DIR TO _HOME
Finally got the single-stage ometa-js launcher to work. This commit represents the working, but not cleaned up version of the code.
The reason I'm checking this in is that it contains a lot of work-in-progress info in the comments, debug prints and extra variables.


Problems fixed:
1. the ometa launcher now doesnt assume the BSParser or BSCompiler - those can be passed in as params
2. It also doesnt do both stages together. This allows composing parse/compile/interpret steps independently. so projects like betterscript can actually use ometa-js as a true external dependency.
	getting this to work was the big achievement. This required adding in crockford's json library

Pending:
- Clean up everything that's not required for this to work.
- determining the type of source - the source|tree param for ometa - is kludgey. see if createInstance can be used instead.