support regex via cli using '/string/'

[AdrianRossouw]

attempt to fix https://github.com/mcollina/docker-allcontainers/issues/5 by adding support for a regex format string:

usage:

./allcontainers.js --matchByName '/elastic.*/'

[AdrianRossouw]

this shouldn't be necessary, as the code is running through 'toRegex' already.

Sikozu:docker-allcontainers adrian$ ./allcontainers.js --matchByName '.*elastic.*'
started { id: 'dd3b2c244d77bd7b880085f7ffb8193067585d0efcf21033d742a1e03210756c',
  image: 'elasticsearch',
  name: 'fuge_elastic_search_1' }