Fix 774, update container request logic to allow multiple containers of different memory amounts to be allocated
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
remove duplicated configuraion merge
Merge pull request #802 from Microsoft-CISL/juwang-DriverServiceConfigurationFix

Fixed: Duplicate merge of DriverRuntimeConfiguration
Updated the license headers in all files
Merge pull request #803 from Microsoft-CISL/weimer_license

Updated the license headers in all files
Updated dependencies and plugins
  * Updated all dependencies (but Hadoop) to their latest versions
  * Updated all plugins to their latest version