Locks cookbook dependencies to known versions

Currently, the latest version of all dependencies are pulled.
If a depended-upon cookbook releases a new major version with breaking
changes, it could break the deis cookbook.

This commit locks cookbook versions to the minor release, which
should be safe as long as cookbook authors follow SEMVER conventions.
Lock docker to 0.31.0

Recent versions require Docker 0.90
Merge pull request #92 from opdemand/carmstrong/lock_dependencies

Locks cookbook dependencies to known versions