Add tests, specify paths, update readme.

Specify path instead of having a dictionary switch: dictionaries can be elsewhere than what you may have hardcoded/specified.
Use path and language name rather than having the user to specify the .dic and .aff separately in the tuple.
Remove HUNSPELL_PROFILE: I don't see this used anywhere in the repo, nor in pyhunspell, or Hunspell/Hunspell.
Shorten from spaCyHunSpell to Hunspell.

tokestermw / spacy_hunspell