SENTRY-515: Disable flaky test testConnectionAfterTicketTimeout (Sravya Tirukkovalur via Lenni Kuff)
SENTRY-432: Synchronization of HDFS permissions to Sentry permissions (Arun Suresh via Lenni Kuff)

This change adds support for synchronizing HDFS permissions with permissions stored in
Sentry. This makes it easy to share data across components (Hive/Impala, MR, Spark, etc)
while managing all privileges in a centralized location - Sentry. This is done using new
plugins to the HMS, HDFS, and Sentry. The HMS plugin pushes table/partition path information
to the Sentry Service, the Sentry Service forwards the path information and all privilege
updates, to the HDFS NameNode plugin, which caches this information and updates the ACLs
accordingly.

The mapping of Sentry privileges to HDFS privileges is:
ALL -> Read/Write access to data files
SELECT -> Read access to data files
INSERT -> Write access to data files
SENTRY-523: Add maven-thrift-plugin back into provider-db pom.xml (Dapeng Sun via Arun Suresh)
SENTRY-408: The URI permission should support more filesystem prefixes (Colin Ma via Lenni Kuff)
SENTRY-74: Add column-level privileges for Hive/Impala (Dapeng Sun and Xiaomeng Huang via Prasad Mujumdar)
SENTRY-328: Need to update DataNucleus version to support proper SQL generation for DB2 ( Tuong Truong via Sravya Tirukkovalur)
SENTRY-525: Fix TestHDFSIntegration test failure
SENTRY-529: Test]org.apache.sentry.tests.e2e.hdfs.TestHDFSIntegrationtestEnd2End test fails after SENTRY-74 (Dapeng Sun via Prasad Mujumdar)
SENTRY-526: Fix SentryStore so that Duplicate grant with same privilge but different case is handled correctly
SENTRY-534: TestRuntimeMetadataRetrieval fails intermittently
SENTRY-536: Disable TestDPrivilegesAtFunctionScope from the cluster run profile (Prasad Mujumdar via Lenni Kuff)
SENTRY-528: Dependent on multiple versions of servlet-api jars lead to throw an SecurityException when running solr e2e test in eclipse (guoquanshen via Gregory Chanan)
SENTRY-540: Fix Sentry test validating special chars in username due to HIVE-8916
SENTRY-140: Orphaned privileges should be garbage collected (Mike Yoder via Lenni Kuff)
SENTRY-555: Ensure groupName returned for dir objects within prefix but not associated with an authz object is not null
SENTRY-545: Disable privilege cleanup by default (Mike Yoder via Lenni Kuff)
SENTRY-556: Remove NPE logging when Sentry Service is not reachable (Reviewed by: Lenni Kuff)
SENTRY-557: Handle Situation when Metastore restarts Listeners thereby resetting the sequenceCounter (Reviewed by : Lenni Kuff)
SENTRY-553: Privilege implies() failed if parent is server privilge and child privilge is URI privilge (Xiaomeng Huang via Lenni Kuff)
SENTRY-555: Make Metastore sync time period configurable (Arun Suresh via Lenni Kuff and Sravya Tirukkovalur)