Set paramiko version > 1.9.0

Ubuntu 12.04 package version for paramiko is 1.7.7.1, which lacks
the additional arguments for exec_command:

  TypeError: exec_command() got an unexpected keyword argument 'get_pty'

1.10.0 was the first version to add get_pty flag.

Change-Id: I3b4d8a6d8a1d10ab002a79824feab8937d160244
Signed-off-by: Paul Belanger <paul.belanger@polybeacon.com>