pin Paramiko on 2.1.3

  The version 2.2.0 depends on PyNaCL which is not well configured currently on buildout.

stack/slapos.cfg

@@ -145,6 +145,7 @@ slapos.recipe.cmmi = 0.7
 stevedore = 1.21.0
 unicodecsv = 0.14.1
 xml-marshaller = 0.9.7
+paramiko = 2.1.3
 
 # Required by:
 # slapos.core==1.3.18