Great additions.

Added:
- Super styled page for uploaded extension. =)
- Readme support (now users can read Readme in GitHub style - thanks to a new plugin).
- File tree full support - now it can be seen after a click on a special link (<< Show file tree >>).
- Noscript support - uploads are done with no ajax, but other abilities are ajaxified with backwards compatibility.
- Zip packages support - now it is easy to unpack and delete zip packages. Zip packages aren't deleted after unpacking - they can be deleted by a click on a delete button.
- New loading state style.
- Some useful fixes and additions to the code.

Now we can say: 'We have a stable extension!'
We can do uploads from PCs and remote servers, unpack zips, read details and delete extensions!

Screenshot:
![upload_extensions_page_new](https://cloud.githubusercontent.com/assets/7805635/3889469/fa0e8984-220e-11e4-9465-1170e7b5b34f.png)