Check apache2 process for keystone/liberty+

Keystone runs under apache2 for liberty+; update amulet
tests to check for apache2 instead of keystone.

Change-Id: I31a683e4acd2f4104453e067bd0e8a0b4e4c73bd

tests/basic_deployment.py

@@ -162,6 +162,9 @@ class SwiftProxyBasicDeployment(OpenStackAmuletDeployment):
             self.swift_storage_sentry: swift_storage_services
         }
 
+        if self._get_openstack_release() >= self.trusty_liberty:
+            service_names[self.keystone_sentry] = ['apache2']
+
         ret = u.validate_services_by_name(service_names)
         if ret:
             amulet.raise_status(amulet.FAIL, msg=ret)