Add TLS support in Bulkomatic Perf test

Add TLS support in Bulkomatic Perf test

- Update MininetKeywords.Start_Mininet_MUltiple_controllers to
support TLS (protocol=ssl). Also speed up the KW by creating
extra mininet SSH connection, instead of using multiple
Utils.Run_Command_On_Mininet (this creates new session)

- Update 100K flow perf test to use TLS connections
(100K_Flows_100DPN_1Node_Perf_Test.robot).

- Remove "--switch ovsk,protocols=OpenFlow13" from suites
using MininetKeywords library as this is not required.

Change-Id: Ice4287bc7982cc23fada368b221bd42d72e5b3da
Signed-off-by: Luis Gomez <ecelgp@gmail.com>