spip - security update

Several vulnerabilities were found in SPIP, a website engine for
publishing, resulting in code injection.

• CVE-2016-3153
  g0uZ et sambecks, from team root-me, discovered that arbitrary PHP
  code could be injected when adding content.
• CVE-2016-3154
  Gilles Vincent discovered that deserializing untrusted content
  could result in arbitrary objects injection.

For the oldstable distribution (wheezy), these problems have been fixed
in version 2.1.17-1+deb7u5.

For the stable distribution (jessie), these problems have been fixed in
version 3.0.17-2+deb8u2.

For the testing (stretch) and unstable (sid) distributions, these
problems have been fixed in version 3.0.22-1.

We recommend that you upgrade your spip packages.