MFH: r409962

Update net/rabbitmq to version 3.6.1.

From the release notes:

This release fixes a number of bugs in 3.6.0 and earlier versions,
as well as one security issue (CVE-2015-8786) in the management
plugin. It also contains usability improvements.

CVE 2015-8786 has not been publicly announced yet.

Security: CVE-2015-8786
Approved by: ports-secteam (miwi)