Introduce `translations_paths`

[markets]

Instead of current method:

# Path to your translation files.
config.load_translations(__dir__ + '/translations/*')

We should introduce a new attribute:

# Path to your translation files.
config.translations_paths = __dir__ + '/translations/*'

Internally, it will call load_translations with current translations_paths instead of an argument. In order to avoid breaking changes, keep the load_translations to accept a path that overrides the translations_paths. The setter translations_paths=, should call the load_translations, so on each change translations will be reloaded.