ubuntu build: Add python-setuptools

Recent ubuntu versions require explicit python-setuptools
dependencies, so we have to oblige.
Signed-off-by: NLucas Meneghel Rodrigues <lmr@redhat.com>

debian/control

@@ -2,7 +2,7 @@ Source: avocado
 Section: python
 Priority: optional
 Maintainer: Lucas Meneghel Rodrigues (lmr) <lookkas@gmail.com>
-Build-Depends: debhelper (>=7.0.50~), python-support (>= 0.6), cdbs (>= 0.4.49), python-yaml
+Build-Depends: debhelper (>=7.0.50~), python-support (>= 0.6), cdbs (>= 0.4.49), python-yaml, python-setuptools
 Standards-Version: 3.8.4
 
 Package: avocado