fix RenderDemo to use configuration of rendering/extensions
fix MarkupDemo
use hash to store template handlers
move special code to template handlets
fix haml
detect erb properly
fix tests to use `=`, check for content_for double output
check output count, enable skipped tests
cleanup unused methods, clarify block_is_type?
disable concatenating `-` in templates for Slim and Haml, add tests for this
Merge pull request #1441 from padrino/fix-output-handlers

Fix and cleanup output handlers