Systest Makefile should accept v11.6.1 and not v11.6.0
Systest Makefile should accept v11.6.1 and not v11.6.0

Problem:
The Makefile supports starting a 11.6.1 big-ip, but the parameter
validation and help refer to 11.6.0.

Solution:
Changed the version number in the parameter checking and help message
for 11.6.1.

Issue #95

michaeldayreads/marathon-bigip-ctlr,michaeldayreads/marathon-bigip-ctlr,michaeldayreads/marathon-bigip-ctlr