Fix 774, update container request logic to allow multiple containers of different memory amounts to be allocated
HttpServeShellCmdtHandler and http server changes

Adding HttpServeShellCmdtHandler to handle  Distributed Shell Command
Moving CommandUtility from reef-websever to helloHttp to share it with
ShellTask
HelloDriver to have all the event handlers
Remove helloTask
Merge branch 'master' of https://github.com/Microsoft-CISL/REEF into juwang-httpServerDistributedShell
Merge remote-tracking branch 'origin' into YingdaReef
minor change to add this. prefix, for consistency
Merge branch 'master' of https://github.com/Microsoft-CISL/REEF into YingdaReef
Merge branch 'YingdaReef' of https://github.com/Microsoft-CISL/REEF into YingdaReef
Merge remote-tracking branch 'origin' into YingdaReef
add synchronized block when managing conatiner request queue
Merge branch 'master' of github.com:Microsoft-CISL/REEF into YingdaReef
Added the JCIP annotations as a dependency
  * Added the Java Concurrency in Practice annotations as a dependency
  * Annotated `Optional` as an example.
Driver Singleton cleanup
  * Removed the named parameter `DriverSingletons` as it wasn't safe with Tang
  * Added the service event handlers to the class `DriverSingletons` as a dependency instead to make sure they are only instantiated once per Driver.
Merge pull request #800 from Microsoft-CISL/weimer_singletons

Driver Singleton cleanup
Merge pull request #799 from Microsoft-CISL/weimer_jcip

Add the JCIP annotations as a dependency
Merge branch 'master' of github.com:Microsoft-CISL/REEF into YingdaReef
minor fixes in YarnContainerManager - code cleanup, simplify
synchronization, use proper logging etc.
Merge pull request #785 from Microsoft-CISL/YingdaReef

Update the container request logic to allow multiple containers of different memory amounts
Merge branch 'master' of https://github.com/Microsoft-CISL/REEF into juwang-httpServerDistributedShell
remove duplicated configuraion merge