Distribute direct charm dependencies

Do not rely on system installed Python packages but distribute the
direct charm dependencies as part of the charms wheelhouse.

As the span of distributions we need to support with reactive
charms widens we will run into compability problems with the
current model.

For further reference see juju/charm-helpers#341 and
juju-solutions/layer-basic#135

Change-Id: I11fb4020dc358c40bf9c1870e94186ba7e97c2db

src/layer.yaml

@@ -3,5 +3,4 @@ repo: https://github.com/openstack-charmers/charm-keystone-saml-mellon
 options:
   basic:
     use_venv: True
-    include_system_packages: True
-    packages: ['python3-lxml', 'python3-cryptography']
+    packages: [ 'libffi-dev', 'libssl-dev', 'libxslt1-dev' ]

src/test-requirements.txt

@@ -6,5 +6,5 @@ stestr>=2.2.0
 python-keystoneclient>=1.7.1
 python-swiftclient
 lxml
-git+https://github.com/openstack-charmers/zaza.git@remove-namespaced-tests#egg=zaza;python_version>='3.0'
+git+https://github.com/openstack-charmers/zaza.git#egg=zaza
 git+https://github.com/openstack-charmers/zaza-openstack-tests.git#egg=zaza.openstack

src/wheelhouse.txt

@@ -0,0 +1,5 @@
+cryptography
+lxml
+
+jinja2
+psutil