Added retries to the SSHTunnel class.
Added retries to the SSHTunnel class.

tonchidot/testbot,nritholtz/testbot,tonchidot/testbot,mhama/testbot,uchihara/testbot,mhama/testbot,uchihara/testbot,joakimk/testbot,joakimk/testbot,nritholtz/testbot