Enable Fedora 19 on DevStack

Fedora uses a special PROMPT_COMMAND for screen terminal types,
which are the default with DevStack.  The PROMPT_COMMAND interacts
in a negative way with the -t and -X and -p flags, causing DevStack
not to work.  To solve this problem, this patch forces PROMPT_COMMAND
to default to /bin/true, triggering no changes to the window title
used within screen.  Also this patch enables F19 as a non-FORCE
distribution.

Change-Id: I2414d9e28dd95b69272e132163b29ed83f73b2f6
Fixes: bug #1196340
diff --git a/functions b/functions
index 70ab999..06d7e7b 100644
--- a/functions
+++ b/functions
@@ -1020,6 +1020,8 @@
         echo "sessionname $SCREEN_NAME" > $SCREENRC
         # Set a reasonable statusbar
         echo "hardstatus alwayslastline '$SCREEN_HARDSTATUS'" >> $SCREENRC
+        # Some distributions override PROMPT_COMMAND for the screen terminal type - turn that off
+        echo "setenv PROMPT_COMMAND /bin/true" >> $SCREENRC
         echo "screen -t shell bash" >> $SCREENRC
     fi
     # If this service doesn't already exist in the screenrc file