Correct documentation of asVersion methods
Context activities as arrays and fallout (bump to 0.3.0)

* Added new ContextActivities class with appropriate properties and unit
  tests, added to readme and build script
* Added significant test coverage for Context which led to other changes
* Correct output of "statement" property as object in context (therefore
  appropriately versioned)
* Add corrections to check for instances of a particular class before
  creating them as subobjects in appropriate locations
* Flesh out initialization of SubStatement
* Fix output of objectType in StatementRef asVersion
Build 0.3.0