SchemaTool validate locations should not return exit 1

HiveSchemaTool can be used by other applications to validate the metastore schema. One of the validation check looks at the location URLs of tables/DBs and returns false which causes HiveSchemaTool to exit 1 to the calling script. Invalid locations although are a problem in some instances, cannot be termed as catastrophic errors in the schema which should cause Hive service failure/unusable. Ideally we should introduce warning levels and error levels in schemaTool validations so the caller can take appropriate action.