Updated SharpZipLib to a hand-built bugfixed copy.

Uses the patch from https://github.com/icsharpcode/SharpZipLib/pull/53 .
Thank you, @novn, for writing this.

Uses the build fixes from https://github.com/Arakis/SharpZipLib for
Mono. Thank you, @Arakis, for providing these.

The branch I built from is at
https://github.com/pjf/SharpZipLib/tree/ckan_gh221

Attentioning @bastianeicher who is maintaining a totally awesome
SharpZipLib patches branch. @novn's patch above fixes the bug
described at http://community.sharpdevelop.net/forums/t/21758.aspx .
There's a test file at
https://github.com/pjf/CKAN/blob/221_ziplib/t/data/gh221.zip which shows
the presence of the bug when combined with the test at
https://github.com/pjf/CKAN/blob/221_ziplib/CKAN/Tests/ZipLib.cs .

Closes #221.
Closes KSP-CKAN/CKAN-meta#33

@malahx: I'll be releasing an updated CKAN client shortly with these
fixes.