[Quota] fixup typo : security_group_rule

Signed-off-by: Nicolas PLANEL <nicolas.planel@enovance.com>
[quota] add unittest for neutron_plugin_contrail.plugins.opencontrail.quota.driver.QuotaDriver.[ _get_quotas, get_all_quotas ]

Signed-off-by: Nicolas PLANEL <nicolas.planel@enovance.com>