qpid: plain auth needs cyrus-sasl-plain package

On fedora 21, qpidd cannot authenticate user, because
cyrus-sasl-plain is no more automatically installed.

This change fixes that.

Change-Id: I74452f40723881291b8c7577e5509da1c0e4e6e5
diff --git a/files/rpms/qpid b/files/rpms/qpid
index 9e3f10a..c5e2699 100644
--- a/files/rpms/qpid
+++ b/files/rpms/qpid
@@ -1,4 +1,4 @@
 qpid-proton-c-devel # NOPRIME
 python-qpid-proton # NOPRIME
 cyrus-sasl-lib # NOPRIME
-
+cyrus-sasl-plain # NOPRIME