Adds paramiko to pip-requires

The whitebox/SSH tests use paramiko, but it is not listed
in the tools/pip-requires. This adds it.

Change-Id: Icd3df69a94446f85772e515a820d8a013f0271f8
fixes: lp bug #1089763
diff --git a/tools/pip-requires b/tools/pip-requires
index e9baed5..3a2283f 100644
--- a/tools/pip-requires
+++ b/tools/pip-requires
@@ -4,3 +4,4 @@
 unittest2
 lxml
 boto>=2.2.1
+paramiko