Box Backup

Add HTTP request logging to S3Simulator.

Add a method on S3Client to check HTTPResponse for errors. Throws a suitable exception if the response status code is not 200 OK.

Fix S3Client handling of "Connection: close" responses. We can't continue to use the same connection after receiving such a response, so close it immediately.

Add utility methods to HTTPRequest and HTTPResponse classes. Allow getting method name of an HTTPRequest, and connection open/closed status of an HTTPResponse.

Refactor to allow sharing code for starting and stopping daemons in tests. The new StartDaemon?() and StopDaemon?() in ServerControl?.cpp/h are generic, and used by StartClient?() and StartServer?() in StoreTestUtils?.cpp/h.

Move InvalidConfiguration? exception to CommonException?. Allows it to be used by S3Store, or in fact anything that uses Configuration.

Refactor BackupStoreInfo? to allow creating them without RaidFiles?. They can now be created using a constructor, and written to any IOStream. Needed for writing them to an S3Store.

Add AccountNumber? to list of config keys checked at runtime. S3Stores don't have account numbers.

Move load_config_file to Test.cpp to allow reuse.

Remove duplicate declaration of test functions.