Fix bug: product desc and details can both match
New listing template: model + words in family

1. Add
BaseMasterTemplateBuilder.match_model_and_words_in_family_with_regex()
to build ListingMatcherTemplate to match on model and optionally on
individual words in family.
Constraints: family must have at least 2 words, model must contain both
alphabetic and numeric characters.
2. Add unit tests.
3. Added SingleMethodMasterTemplateBuilder to simplify setting up a
master template builder that runs a single method only.