Run MyriadMesosScheduler inside YARN's resource manager JVM.

The objective of this change is to run MyriadMesosScheduler inside YARN's resource manager JVM.

1. Added Myriad{Fair,Capacity,Fifo}Scheduler classes that extend from Yarn's {Fair,Capacity,Fifo}Scheduler classes respectively.
2. Added build dependencies on Hadoop.
3. Encountered slf4j's "multiple binding" conflicts because drop wizard uses
   logback implementation while YARN uses slf4j-log4j12 implementation for slf4j API.
   After discussions with Mohit, we've decided to remove dependencies on drop wizard.
4. Refactored the rest of the code to that effect. Retained non-conflicting deps like
   codahale metrics, jackson's dataformat/databind/annotations/yaml and hibernate validator.
5. Added build rules to package the myriad jar and the dependencies to build/libs dir.
   These DO NOT INCLUDE hadoop jars and their dependencies as the intent is to
   deploy myriad jar and it's deps into an existing YARN installation.

Build and Deployment guidelines:
1. From myriad dir in the local git repo, run "./gradlew jar".
2. This should produce myriad-0.0.1.jar and other deps under build/libs dir.
3. Copy build/libs/*.jar to HADOOP_HOME/share/hadoop/yarn.
4. Modify HADOOP_HOME/etc/hadoop/yarn-site.xml to have the following entry:
  <property>
    <name>yarn.resourcemanager.scheduler.class</name>
    <value>com.ebay.myriad.scheduler.yarn.MyriadFairScheduler</value>
  </property>
5. Restart Resource Manager process.

CAVEATS:
- The REST API to myriad is currently broken as we eliminated the dependencies on dropwizard.
  We need to bring up a web app for myriad and expose the
  REST API through that.
- Mesos also requires a native library (libmesos.so). Our build process currently
  does not add that to myriad jar. We need to manually add that to YARN's native lib dir
  $HADOOP_HOME/lib/native.

I'll open tasks for both the above and track them separately.