atomic: add pid to PidFileTaken
machine: add new_session parameter
Update .travis.yml
add islink to path package
Merge pull request #103 from AntoineD/master

add islink to path package
Tweak ParamikoMachine for python3 compatibility.
Merge pull request #104 from RyanBallantyne/master

Tweak ParamikoMachine for python3 compatibility
use generator comprehension instead