Added source url to API, helps fixing dokuwiki-extension-manager issue 28
Allow screenshot/logo url for plugins in the API
Merge branch 'master' of github.com:splitbrain/dokuwiki-plugin-pluginrepo
added thumbnailurl field

this links to a resized version of the screenshot, dokuwiki.org takes
care of the resizing
Merge remote-tracking branch 'upstream/master'