Run setup_develop for tempest.

This setups the development environment for tempest. Without
running setup_develop for tempest import tempest.* breaks
outside of the tempest directory.

Change-Id: I6954733d68125dd116cc9bfa58b9aece674405c3
diff --git a/lib/tempest b/lib/tempest
index 4d91d90..5ad9b32 100644
--- a/lib/tempest
+++ b/lib/tempest
@@ -55,6 +55,7 @@
 
 # configure_tempest() - Set config files, create data dirs, etc
 function configure_tempest() {
+    setup_develop $TEMPEST_DIR
     local image_lines
     local images
     local num_images