Add instructions on building lighttpd for Debian stable.

Some Owncloud features (Namely contact editing) don't work with Lighttpd on Debian stable because it doesn't support the PATCH verb. Add instructions on how to patch that functionality in and build the resulting package.
Correct capitalization of ownCloud
Merge pull request #239 from ssweeny/patch-2

Add instructions on building lighttpd for Debian stable.