* Replaced AssetType in Metadata with ContentType (MIME type)
* Added Logger.cs, HttpServer.cs, and HttpRequestSignature.cs since AssetServer no longer depends on OpenMetaverse.dll
* Upgraded to the latest OpenMetaverse which splits OSD off into OpenMetaverse.StructuredData.dll
* Force connection pooling off in MySQLStorage backend to attempt to fix resource leak
* Added utility methods to convert from SL AssetType to Content-Type and back