Allow page size to be specified per CMR search request

[chuckwondo]

The page size for CMR searches is specified in a maap.cfg file, and cannot be specified on a per-request basis. This means, for example, that no matter how many granules I request for a search (specified by the limit parameter that can be specified per request), the page size is fixed.

In the ADE, the page size in maap.cfg is 20, which causes very poor performance (see #25) for large enough search requests. For larger search requests, it should be possible to specify larger page sizes on a per request basis (like limit can be specified per request).