Added Drag/Drop support for images.

Dragging an image file into everpad now attaches it to the note and inserts it at the current cursor location.
Gnome shell support, yep
Merge branch 'dragdrop_image' of git://github.com/mhaggag/everpad into mhaggag-dragdrop_image

Conflicts:
	everpad/pad/editor.py
Merge branch 'master' of github.com:nvbn/everpad
fix merging issues
fix #165
attach all files on drop
fix #163
add --all-notes for #147
fix launcher progress bar
update translations
bump to 2.3
fix packaging
Update README.rst
Fixed urls not opening due to #146 fix, also modified url opening to Ctrl-click
Merge pull request #167 from cas--/Bug/UrlsNotOpening

Fixed urls not opening due to #146 fix, also modified url opening to require Ctrl-Click
Add email note option to editor
Add keyshortcuts to editor, also change Ctrl+q to Ctrl+w and save on close
Add key shortcuts to All Notes
Add confimation to close without save
Merge pull request #168 from cas--/Feature/EmailBtn

github.com/nvbn/everpad/issues/140