Add options for development bindep install

This adds a -bindep option to the key development library install
functions.  With this option the bindep.txt file will be referenced
and the relevant packages installed.

Change-Id: I856f1f59fca49b6020920d8f859b797f3b904300
diff --git a/stack.sh b/stack.sh
index 144c233..ad1359e 100755
--- a/stack.sh
+++ b/stack.sh
@@ -801,6 +801,11 @@
 # Install required infra support libraries
 install_infra
 
+# Install bindep
+$VIRTUALENV_CMD $DEST/bindep-venv
+# TODO(ianw) : optionally install from zuul checkout?
+$DEST/bindep-venv/bin/pip install bindep
+
 # Extras Pre-install
 # ------------------
 # Phase: pre-install