Boost exact matches x2 over fuzzy_like_this

Extremely similar `fuzzy_like_this` strings are scored the same or incorrectly due to the nature of `fuzzy_like_this`. In one of our integration tests, `ordertet` was scored higher than `ordertest` when searching for `ordertest`. (For some reason this was only happening when the `testSearchRelevanceOrderbyQuery` test was run by itself.)

This PR uses a `should` query instead of `must`. The clauses are `multi_match` and `fuzzy_like_this`. `multi_match` is boosted higher so that exact matches score higher than fuzzy ones.

Further reading:
http://elasticsearch-users.115913.n3.nabble.com/fuzziness-amp-score-computation-td4052341.html
I like your thinking here on the order / relevance testing