add more comments
fix local mode master proxy bug
fix config override issue
Update Local.scala
Add global clock service
Merge remote-tracking branch 'upstream/master'
Merge branch 'master' of https://github.com/clockfly/gearpump

Conflicts:
	src/main/scala/org/apache/gearpump/cluster/main/Local.scala
fix the code style
fix the comments
fix style
improve the code
refactor the naming
refine the naming and code structure
refine the code
Use alias for timestamp, taskgroupid, and taskindex id
remove a code nitch
refine the code
make a copy of MInClockSince head message
fix the comments
replace message type from string to message type with timestamp: Message