SAK-23179 update purepoms parent to 2.8.7

git-svn-id: https://source.sakaiproject.org/svn/msgcntr/branches/msgcntr-2.8.x@119107 66ffb92e-73f9-0310-93c1-f5514f145a0a
[maven-release-plugin] prepare release msgcntr-2.8.4

git-svn-id: https://source.sakaiproject.org/svn/msgcntr/branches/msgcntr-2.8.x@119108 66ffb92e-73f9-0310-93c1-f5514f145a0a
[maven-release-plugin] prepare for next development iteration

git-svn-id: https://source.sakaiproject.org/svn/msgcntr/branches/msgcntr-2.8.x@119110 66ffb92e-73f9-0310-93c1-f5514f145a0a