update changelog for v2.8.6

updated changelog for v2.8.5

updated changelog for v2.8.4

updated changedlog for v2.8.3

updated changelog for v2.8.2

updated changelog for v2.8.1

updated changedlog for 2.8.0

updated changelog for v2.7.9

updated changelog for v2.7.8

have bluecherry.service file for both rpm and debian packaging