Previously, not setting a security group leads to an invalid
signature (when using api keys). This was caused b/c
an extra securitygroupid was added with '' as its value.
This was calculated as a part of the signature, but dropped
from the request, leading to the error:
unable to verify user credentials and/or request signature
This commit only adds a securtygroupid param if the result of
the querying for groups does not return []. This will prevent the
extra security group from being added.
