Removed unnecessary require.
Basic HTML and PDF export.
Open exports always in new windows.
Format change.
Format change.
Add title in full html file.
Basic functionality for ePub and mobi export.
Get combined name as full_name
Copy images to epub/mobi export; if remote, than download them.
Reduces number of errors for generated epub.
Basic tests for export functionality; dropped mobi support due to complexity.
Improvements for download of epub.
Merge pull request #2 from team-sb/feature-export

Basic export functionality for full html, pdf and epub. Realized by kitabu and wicked_pdf.