Add development libraries needed by Pillow

Change I8da7dd95ae24cf06dc7bdc300fcf39947a6df093 added Pillow build deps
to nodepool thick slaves.  This means that Pillow 3 will work in unit
tests.

Make the matching change to allow Pillow 3.0.0 to work under devstack.

The longer term aim is to remove temporary upper cap.

Change-Id: I2bec8cf1bfeaaa6ae329704229fdeb86d26e55c7
diff --git a/files/rpms/general b/files/rpms/general
index cfd9479..40b06f4 100644
--- a/files/rpms/general
+++ b/files/rpms/general
@@ -12,6 +12,7 @@
 java-1.7.0-openjdk-headless  # NOPRIME rhel7
 java-1.8.0-openjdk-headless  # NOPRIME f21,f22
 libffi-devel
+libjpeg-turbo-devel # Pillow 3.0.0
 libxml2-devel # lxml
 libxslt-devel # lxml
 libyaml-devel