Added upload of file thru ajax drag and drop

- Added secret key generation in create_config
- Uploaded files can be accessed in/uploads/
import in top of file
Added empty uploads folder
Fixed error with create_config adding a comma to FONT_NAME
Refactored preview functionality, removing useless complexity. Downside is page position is lost when clicking preview button from editing a post. Deal with it.
Fixed support for CJK characters in the post URL. Thanks yin8086!
Merged danielmagnussons / simple (for drag and drop uploads)
Refactored drag-and-drop uploads. Now supports multiple files and you can click an uploaded file to quickly append the image into the markdown editor.
Update readme.md
Merge remote-tracking branch 'remotes/orf/master'

Conflicts:
	simple.py
	templates/edit.html