Fail when ssl parameters are missing and rabbit_use_ssl is set to true

This commit causes the run to fail is rabbit_use_ssl parameter is set
to true but the ssl related parameters remains undef.

Change-Id: If621de7ed4432c4ef79d18cee4da822ebadb0a4f
(cherry picked from commit 85a98e13e82e7c87549b92cbd3bb114d4afbde43)
Merge "Fail when ssl parameters are missing and rabbit_use_ssl is set to true" into stable/icehouse