CBQE-0: failsafe paramiko import

in cases paramiko where is not used it's ok if ImportError is thrown.

Change-Id: I724b3a2df6330aa647403d2179cb9ad1063539e1
Reviewed-on: http://review.couchbase.org/36868
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>