[SPARK-10514] [MESOS] waiting for min no of total cores acquired by Spark by...

[SPARK-10514] [MESOS] waiting for min no of total cores acquired by Spark by implementing the sufficientResourcesRegistered method

spark.scheduler.minRegisteredResourcesRatio configuration parameter works for YARN mode but not for Mesos Coarse grained mode.

If the parameter specified default value of 0 will be set for spark.scheduler.minRegisteredResourcesRatio in base class and this method will always return true.

There are no existing test for YARN mode too. Hence not added test for the same.

Author: Akash Mishra <akash.mishra20@gmail.com>

Closes #8672 from SleepyThread/master.