litmus: release 0.13

[Joe Orton]

Download: http://www.webdav.org/neon/litmus/litmus-0.13.tar.gz
Signature: http://www.webdav.org/neon/litmus/litmus-0.13.tar.gz.asc
 MD5: 7c081e182214e771bc615232ef475b00  litmus-0.13.tar.gz
SHA1: 42ad603035d15798facb3be79b1c51376820cb19  litmus-0.13.tar.gz

Changes in version 0.13:
* Changed tests:
 - locks: owner_modify checks that PROPPATCH works against a locked
   resource (thanks to Javier Godoy)
* Support PKCS#12 client cert with --client-cert/-c (Alejandro Alvarez Ayllon)
* Update to neon 0.29.6.