Allows skill to dynamically define intents or entities

[zeronounours]

Is your feature request related to a problem? Please describe.
Some skills my require dynamic definition of padatious entities to prevent matching requests intented for other skills.
See MycroftAI/skill-homeassistant#64 and MycroftAI/skill-homeassistant#104

It can currently be done with file within resource directories, but it is not a clean solution.

Describe the solution you'd like
New methods should be implemented to dynamically load new entities or intents in padatious with any wanted name. For instance:

   def register_entity_file_as(self, filename, name):

Describe alternatives you've considered
Currently skill-homeassistant provides absolute path to a temporary file to MycroftSkill.register_entity_file(). This method may be updated to only use as name the base name of the file and not the full path.