DRILL-4335: Apache Drill should support network encryption.
NOTE: This pull request provides support for on-wire encryption using SASL framework. The communication channel that are covered are:
1) Between Drill JDBC client and Drillbit.
2) Between Drillbit to Drillbit i.e. control/data channels.
3) It has UI change to view encryption is enabled on which network channel and number of encrypted/unencrypted connections for
user/control/data connections.
close apache/drill#773
