Updated firefox and thunderbird packages fix security vulnerabilities

Several flaws were found in the processing of malformed web content. A web page containing malicious content could cause Firefox or Thunderbird to terminate unexpectedly or, potentially, execute arbitrary code with the privileges of the user running Firefox or Thunderbird (CVE-2013-5609, CVE-2013-5616, CVE-2013-5618, CVE-2013-6671, CVE-2013-5613). It was found that a subordinate Certificate Authority (CA) mis-issued an intermediate certificate, which could be used to conduct man-in-the-middle attacks. This update renders that particular intermediate certificate as untrusted (MFSA 2013-117). The rootcerts and nss packages have been updated to fix the MFSA 2013-117 issue. The thunderbird-lightning package has been updated to a version that is compatible with the updated thunderbird.