Docker.erb: add quotes around variable values
Docker.erb: enable the use of an array for no_proxy value

This should keep compatibility with current version (in 1.2.2, no_proxy is a String instance) and allows one to use a list for configuration which permits the use of YAML references.
Docker_spec: Update regression tests for proxy values
Docker.erb: Unify with /etc/default/docker.erb
Docker.erb: Unify with /etc/default/docker.erb
Merge pull request #122 from commial/master

No_proxy as an Array