Added preview view for HTML files
Added icon to preview menu entry
Added automatic refreshing of open preview tabs on file save
Added Reload-On-Save to settings
Renamed preview to html_preview
Added dependency for markdown-js
Added markdown preview handler
Adjusted CSS to accommodate markdown changes
Updated preview FileHandler names
Merge pull request #366 from invokr/feature--preview

Added preview view for HTML files
Fix markdown previewer dependency
Fix markdown previewer