Turn on build_tests and unittests

Hopefully will workaround crosbug.com/31658

BUG=chrome-os-partner:9958
BUG=chromium-os:31658
TEST=cbuildbot_config_unittest

Change-Id: I94daed8db52ca5e0dc80b95f978863025e84e1b6
Reviewed-on: https://gerrit.chromium.org/gerrit/24879
Reviewed-by: Eric Blake <eblake@chromium.org>
Tested-by: Eric Blake <eblake@chromium.org>
diff --git a/buildbot/cbuildbot_config.py b/buildbot/cbuildbot_config.py
index fa59de5..1e7fb0e 100755
--- a/buildbot/cbuildbot_config.py
+++ b/buildbot/cbuildbot_config.py
@@ -955,9 +955,8 @@
   push_image=False,
   uprev=True,
   overlays=constants.BOTH_OVERLAYS,
-  images=['base', 'factory_install'],
-  build_tests=False,
-  unittests=False,
+  build_tests=True,
+  unittests=True,
   vm_tests=None,
   prebuilts=False,
 )