Add dependencies for paramiko 2.0

Paramiko version 2.0 has been released. It now uses the Python library
cryptography. Installing this requires additional system packages. This
commit adds in the appropriate packages required by cryptography based
on its documentation [1].

An alternative approach would have been to constrain the version of
Paramiko however the project describes the 1.x versions as relying on
insecure dependencies [2].

[1] https://cryptography.io/en/latest/installation/
[2] http://www.paramiko.org/installing.html

Change-Id: I0151a7400d0f93c4ee85eb078846f90ab54288f7

other-requirements.txt

@@ -9,3 +9,7 @@
 # is better to have this file empty, otherwise OpenStack-CI
 # will fall back to installing its default packages which
 # will potentially be detrimental to the tests executed.
+
+# Requirements for Paramiko 2.0
+libssl-dev
+libffi-dev

run_tests.sh

@@ -19,7 +19,7 @@ FUNCTIONAL_TEST=${FUNCTIONAL_TEST:-true}
 
 # prep the host
 if [ "$(which apt-get)" ]; then
-  apt-get install -y build-essential python2.7 python-dev git-core
+  apt-get install -y build-essential python2.7 python-dev git-core libssl-dev libffi-dev
 fi
 
 # get pip, if necessary