(#4) - pouchdb-wrappers based port

My shot at porting filter-pouch to use my [pouchdb-wrappers](https://www.npmjs.org/package/pouchdb-wrappers) lib.

Advantages:
- Less code
- More supported function signatures (``db.put({}, "id", 'rev")`` e.g.)

Disadvantage:
- An extra dependency, with a codebase you probably aren't currently familiar with. (I'm currently open to bug reports/questions/suggestions, but it's not the same.)

If the advantages outweight the disadvantages I don't know, it's in the end your lib to maintain. Tests still pass without any modifications, coverage is still 100%.