Add additional parameters for search api

http://wiki.openstreetmap.org/wiki/Nominatim

street=<housenumber> <streetname>
city=<city>
county=<county>
state=<state>
country=<country>
postalcode=<postalcode>
   (experimental) Alternative query string format for structured
requests.
   Structured requests are faster and require less server resources.
   DO NOT COMBINE WITH q=<query> PARAMETER.
Remove second street method
Added undocumented criteria featuretype to Search.

This allows restriction by certain area feature, like city,
so results from another city specified in the query won’t
be mixed to the result. For some reason this feature is not
documented in public API doc of Nominatim.