Added the ability to query a single store using AdminClient / admin tool

Added a test and also validated manually:

[csoman@csoman-ld voldemort]$ bin/voldemort-admin-tool.sh --get-metadata test-to-all --url tcp://localhost:6666
[15:14:34,628 voldemort.client.AbstractStoreClientFactory] INFO Client zone-id [-1] Attempting to get raw store [voldsys$_metadata_version_persistence]  [main]
[15:14:34,660 voldemort.client.AbstractStoreClientFactory] INFO Client zone-id [-1] Attempting to get raw store [voldsys$_store_quotas]  [main]
localhost:0
Key - test-to-all
version() ts:0
: <stores><store>
  <name>test-to-all</name>
  <persistence>memory</persistence>
  <routing-strategy>consistent-routing</routing-strategy>
  <routing>client</routing>
  <replication-factor>1</replication-factor>
  <preferred-reads>1</preferred-reads>
  <required-reads>1</required-reads>
  <preferred-writes>1</preferred-writes>
  <required-writes>1</required-writes>
  <key-serializer>
    <type>string</type>
    <schema-info version="0">UTF-8</schema-info>
  </key-serializer>
  <value-serializer>
    <type>string</type>
    <schema-info version="0">UTF-8</schema-info>
  </value-serializer>
</store></stores>