Fix security group rule conflict

Fix security group rule conflict

-open_icmp_ssh function, that creates security
 group rules for icmp and http (here the name of
 the function is misleading),  is splitted into 2
 new functions one for each rule (open_icmp() and
 open_http_port()).
 Test cases that used the old function have been
 updated

-In the original implementation of open_icmp_ssh()
 and open_bgp_port(), the direction parameter was
 missing. This was leading to an error message

-A check for the existence of security group rule
 has been added and used before the creation of each
 security group rule. If a rule already exists,
 an info message is printed and the testcase
 continues

This change is strongly dependent on https://gerrit.opnfv.org/gerrit/#/c/31925
of Functest repo. NOT TO BE MERGED before

JIRA: SDNVPN-103

Change-Id: Icb96954556f6d7294cf3454f045dbca4b9be672d
Signed-off-by: tomsou <soth@intracom-telecom.com>