finished initial impl of fuzzy search

you can do a manual fuzzy term search using the FuzzyQuery struct
or, more suitable for most users the MatchQuery now supports
some fuzzy options.  Here you can specify fuzziness and
prefix_length, to turn the underlying term search into a fuzzy
term search.  This has the benefit that analysis is performed
on your input, just like the analyzed field, prior to computing
the fuzzy variants.

closes #82