enable tokens for tree/twee

bump up to ruamel 0.10.11 to fix install issue

keys command tests, switch pyyaml to ruamel.yaml

- add tests for keys command
- switch pyyaml to ruamel.yaml
- use ExoConfig from exo.py
- fixes for Python 2.6
- add SSL dependencies for Python < 2.7.9

bump to pyonep 0.13.4

0.9.20 plugin debug output fix

0.9.19 fix meta test and add plugin example

fix spurious output in search, update usage in docs

add note about 2.6