Add oslo.service to devstack

Add the ability to switch on oslo.service master using
LIBS_FROM_GIT

Change-Id: I00fe7776aea005b6d4e0a84fce54f33a862b57e3
diff --git a/lib/oslo b/lib/oslo
index be26668..554bec8 100644
--- a/lib/oslo
+++ b/lib/oslo
@@ -37,6 +37,7 @@
 GITDIR["oslo.policy"]=$DEST/oslo.policy
 GITDIR["oslo.rootwrap"]=$DEST/oslo.rootwrap
 GITDIR["oslo.serialization"]=$DEST/oslo.serialization
+GITDIR["oslo.service"]=$DEST/oslo.service
 GITDIR["oslo.utils"]=$DEST/oslo.utils
 GITDIR["oslo.versionedobjects"]=$DEST/oslo.versionedobjects
 GITDIR["oslo.vmware"]=$DEST/oslo.vmware
@@ -76,6 +77,7 @@
     _do_install_oslo_lib "oslo.policy"
     _do_install_oslo_lib "oslo.rootwrap"
     _do_install_oslo_lib "oslo.serialization"
+    _do_install_oslo_lib "oslo.service"
     _do_install_oslo_lib "oslo.utils"
     _do_install_oslo_lib "oslo.versionedobjects"
     _do_install_oslo_lib "oslo.vmware"