Add HTTP username and password, ca-cert and no-verify parameters

[sadok-f]

In order to benchmark an elasticsearch cluster which is running in SSL and with X-pack security enabled (HTTP authentification) I make this PR to:

• Add HTTP username and password parameters.
• Add ca-cert parameter
• Add no-verify parameter

[roiravhon]

Great. I assume you tested both SSL and none-SSL scenarios with the new code, right?

[sadok-f]

Yea both scenarios work well.

[roiravhon]

Awesome. Thanks for that!

[sadok-f]

Great !