How might we improve performance?

[stevepolitodesign]

It appears that initializing Mitie::NER is a slow operation, especially in production-like environments.

[stevepolitodesign]

I think one thing we could explore is caching the instance, so that it can be re-used so long as the path remains unchanged. The first initialization would be slow, but subsequent calls would be fast.

[stevepolitodesign]

This was addressed in #86