Port  API Tests Enhancements

Add function to update port with security groups
   -Function take list of security groups name
    as parameter
   -Create security group based on the names in
    the parameter
   -Create a port without security group
   -Update the port with the security group
   -Verify that security groups are updated in
     the port  successfully

Add a test to update the port with security group
    -Call the update port with security groups
     function with one name of security group

Add a test to update the port with two security
group
   -Call the update port with security groups
    function with two names of security groups

Change-Id: I490f3c7eb66e74f4185588870f9b2b44b54bd64b
Merge "Port  API Tests Enhancements"