Fixes Bug 1436- Python3-Cryptography dependencies updated

Change-Id: I533d54312c389c6c0cadf435b5eee3bf4a52ff67
Signed-off-by: João Fonseca <jpedrofonseca@av.it.pt>

docker/RO/Dockerfile

@@ -46,7 +46,12 @@ RUN apt-get update && DEBIAN_FRONTEND=noninteractive apt-get install -y python3-
     python3-osm-rovim-openstack${RO_VERSION} python3-osm-rovim-openvim${RO_VERSION} \
     python3-osm-rovim-vmware${RO_VERSION}
 
-# ensure right version is installed as pyhton3-ccryptography install an old version
+# ensure right version is installed as python3-cryptography install an old version
+# Since release 3.4 of python3-cryptography rust is an dependency
+
+RUN DEBIAN_FRONTEND=noninteractive apt-get -y install build-essential libssl-dev libffi-dev \
+    python3-dev cargo
+
 RUN python3 -m pip install --upgrade "cryptography>=2.5"
 
 VOLUME /var/log/osm