begin work on dsl refactoring
finish refactor and add test for script dsl format
add multi dsl test
integrate DSL parsers into seed tasks
refactor seed:scripts to use ScriptDSL, update tests
update comment
Work on image-based match puzzle.
Merge pull request #610 from code-dot-org/dsl_refactor

DSL refactor
Script images may now be served from /script_assets/ base URL.
Merge branch 'finished' into imagematch

Conflicts:
	config/process_match.rb
Add banner and slot height support to .match files.
Make description and banner both optional for multi.
Dashboard Dropbox changes
Merge branch 'finished' into delivered