[NEXUS-6680] Yum metadata full rebuild

That nukes complete cache folder and task field
rename.
remove yecht dependency from jruby since it has an unclear license and the library is not used
Merge pull request #797 from mkristian/no-yecht-transitive-dep

remove yecht dependency from jruby
Update to buildsupport 7
Update headers of ruby sources
Add dependency to org.bouncycastle:bcprov-jdk15on needed by ldap test suite
Merge pull request #796 from sonatype/nexus-2.11.x-NEXUS-6680-full-rebuild

[2.11.x][NEXUS-6680] Yum metadata full rebuild
Merge remote-tracking branch 'origin/nexus-2.11.x' into nexus-2.11.x-NEXUS-6899-yum-versions