[Breaking] Modify ShellOut#run_command to take an options Hash.

This will allow users of the method to pass additional configuration to
the shelled out command such as environment variables, current working
director, customized timeout value, etc.

This mixin module (Kitchen::ShellOut) is used internally and exposed to
Driver implementors as `#run_command` in all `Driver::Base` subclasses.
Merge pull request #73 from opscode/run-command-with-hash-options

[Breaking] Modify ShellOut#run_command to take an options Hash.