Create initial search service

[analogrelay]

[Ported from https://github.com/NuGet/NuGetApi/issues/11]

This is the first public service in APIv3 - We'll create a simple search API that has the following main improvements over the current search system:

1. Search Index contains ALL packages
2. Relevance is driven by recent popularity data instead of all-time popularity
3. Independent service running Lucene with an in-memory index for improved performance.

And more!

Test Notes

Using the Admin Key in the CSCFG file, you can access https://<search service host>/search/console in order to test various queries. Since the service is not yet integrated into the Gallery, this provides a simple way to bash on the data and ensure a few things:

1. When a new package is uploaded, it appears in the index within 2 minutes
2. When a new version of an existing package is uploaded, it appears within 2 minutes
3. When a package is listed/unlisted, the index is updated within 2 minutes (ensure "Ignore Filter" is not checked as that will ignore the listed/unlisted filter)
4. When a package is edited, the index is updated about 2 minutes AFTER the edit is finalized by HandlePackageEdits.

[analogrelay]

Done!