new plugin screenshot base is http://s.w.org/plugins/
accept plugin slug as second script argument
use HTTPS for screenshots, to avoid insecure content warnings with pages loaded over SSL
fix plugin screenshot base for screenshots both in assets and in plugin dir
Merge pull request #13 from sunchaserinfo/upstream

new plugin screenshot base
Merge branch 'master' of github.com:benbalter/WP-Readme-to-Github-Markdown into upstream-merger

Conflicts:
	index.php