Adding basic support for wildcard queries.

Hi,

I needed wildcard queries in a personal project that I'm using elastic library. Quickest thing that I could was to duplicate prefix query code, and make them compatible with the wildcard queries.

I know that this might not be a good patch (since it is just duplicate of prefix query code with wildcard keywords), but it worked for me, and might be useful for someone else.

I have tested this with go1.3.3 darwin/amd64, on OS X with Elasticsearch 1.4.1 on Debian 7.7.

Best regards,
Yaşar Şentürk