The extension is built on top of Kango framework: http://kangoextensions.com/
In order to build the extension use this command:
kango.py /path/to/local/copy
You'll then get a .crx (for Chrome), .xpi (for Firefox) and .oex (for Opera) files inside output directory.
Chrome: https://chrome.google.com/webstore/detail/html2haml/gbccoikoopfdljdildkillfbcapldcmh
FireFox: https://addons.mozilla.org/ru/firefox/addon/html2haml/
Don't forget to copy output/safari/htmlhaml_x.x.x.safariextension/Info.plist to the safari directory after
version increment. Also you need manualy build the .safariextz file via Safari's Extension Builder and put it
in same folder. This is needed due to the reason Apple doesn't host the extensions on their servers, so both
manifest and extension files should be hosted by developer himself.