Merge pull request #5 from adlpz/master

Only return collections in reader for homogeneity
Improvements required downstream

- Added delimiter parameter all the way up to the CSV parser
- Added post-process callable registration for arbitrary functionality to be run after every imported entity
	+ Callables accept entities and may modify then
	+ Callables may perform validation and throw InterpreterException, which will be handled as any other interpreter exception of the system.