Enhancement: Add date parameters to search request

[dan-king]

Enhancement request: Add data parameters to the search request query.

https://wiki.ushahidi.com/display/WIKI/SwiftRiver+API+Search+Resources

Currently the search returns drops for all dates. Would like to limit it to certain dates.

Current workaround is to look at date values in the response and ignore if out of range, but since the count is limited the end results may be less than the true count expected.