NEXUS-7789: Scheduling API

Moved out the scheduling bits into new bundle
Merge remote-tracking branch 'origin/master' into NEXUS-7789-scheduling-api
remove pointless comment
NEXUS-7789: Splitting packages across bundles
NEXUS-7789: Trim off meaningless NX prefix from class names
NEXUS-7789: Renames

NexusTaskFactory -> TaskFactory
NexusTaskScheduler -> TaskScheduler
NEXUS-7789: Moved components into nexus-scheduling-api and renamed the bundle
Merge pull request #904 from sonatype/NEXUS-7789-scheduling-api

NEXUS-7789: Scheduling API