Simplified element-level substitution handling
Separate out blog test app from PoC;
Update to use nexted contexts for injection & substitution;
Move model handling to TemplateRenderer;
Fix handling of nested injection to prefer getters over fields;
Blog sample:
Flesh out blog model/DAO;
Add post view page & handler;
Add post edit form;
Add 404 handling;
Add global navigation;
Engine:
Add doctype to output
Strip data-z-* attributes during processing
Fix substitution adding whitespace due to prettyprint;
Add post link to blog nav;
Move getElementPath to DocumentContext