skip the volumes mounted when deleting the volumes of container.
use Binds key in hostConfig to detect volumes mounted from external.
Minor code simplification for Containers api
Refactor State to be 100% thread safe
Engine: integer job status, improved stream API

* Jobs return an integer status instead of a string
* Status convention mimics unix process execution: 0=success, 1=generic error, 127="no such command"
* Stdout and Stderr support multiple thread-safe data receivers and ring buffer filtering
Engine: better testing of streams and of basic engine primitives. Coverage=81.2%