This commit adds support for the compound queries "bool", "boosting",
"constant_score" and "dis_max". The "function_score" query is not
supported yet.
Compound queries are simple. They act just like simple queries, except
that they are recursive, wrapping other simple/compound queries.
For example:
esquery.Bool().
Must(Term("user", "kimchy"), Term("author", "kimchy")).
Filter(Term("tag", "tech"))
Ido Perlmuter