Implement markdown editor and preview window.
Adding header license and end of file NL
clean up content view
Adding show preview and show source
clean up button style
override reconcile
Adding missing semi
refactor markdown nits
Merge pull request #2027 from financeCoding/markdown_action

Markdown preview support
Merge remote-tracking branch 'upstream/master' into improve-font-rendering

Conflicts:
	ide/app/spark_polymer.css