Chef 13 compatibility

[trivoallan]

Updated cookbook so that it depends on "poise-python" cookbook instead of the deprecated "python" cookbook.

[scalp42]

@coderanger any chance to see these PRs make it upstream?

[sergderevyanko]

@trivoallan are you going to fix failed checks and get pr merged?

[trivoallan]

@sergderevyanko it seems the problem is not with the PR but with the build system :

$ rvm use 2.1.4 --install --binary --fuzzy
ruby-2.1.4 is not installed - installing.
Searching for binary rubies, this might take some time.
Requested binary installation but no rubies are available to download, consider skipping --binary flag.
Gemset '' does not exist, 'rvm ruby-2.1.4 do rvm gemset create ' first, or append '--create'.
The command "rvm use 2.1.4 --install --binary --fuzzy" failed and exited with 2 during .

https://travis-ci.org/poise/supervisor/jobs/275813323