use oslo.db module

* Use oslo.db module instead of rally.openstack.common.db
* Remove rally/openstack/common/db

Change-Id: I78e29810f4bf6cc624417744dd74f15ef2281edf
Add sla checking

SLA (Service-level agreement) is set of details for determining
compliance with contracted values such as maximum error rate or
minimum response time.

Add two criteria:
 maximum time per iteration
 maximum error rate

Change-Id: I1212bd684831461a7d7e33636d45a6d346e3b574
Blueprint: task-success-criteria
Fix wrong attribute name used for http status

* Use status_code instead of incorrect http_status

Change-Id: I464f28dcdf96542b8d5420133f13d4150da37aaa
Closes-Bug: #1335154
Merge "Fix wrong attribute name used for http status"
Fix creation of ICMP security group rule when using Neutron

Update ICMP allow rule to use the value -1 for to_port and
from_port parameters as ICMP protocol does not have port.

Change-Id: Idc76e156f07b99574b6b77dba803d5a4f823380b
Closes-bug: #1336704
Merge "Fix creation of ICMP security group rule when using Neutron"
Updated rally gate scenarios

Change-Id: I021e4be45cf3e9d92c9e099cec63ae844831c995