wireshark: bump to version 1.8.6

Multiple vulnerabilities and many bugs have been fixed. See the release
notes for details:

  http://www.wireshark.org/docs/relnotes/wireshark-1.8.6.html
wireshark: update homepage URL
Merge pull request #524 from bjornfor/wireshark

Wireshark: bump to version 1.8.6 + homepage URL update