Fix bug in HTTP server's form-data parsing

Did not handle a non-empty preamble properly
Refactor Rhizome manifest validation

New function returns text describing the failed validation
Rhizome Java API: list bundles
Rhizome Java API: get manifest

Fixes assertion violation in GET /restful/rhizome/<BID>.rhm when <BID>
not found
Rhizome Java API: get raw payload

Added more "Serval-Rhizome-Bundle-xxx" headers to /restful/rhizome/
responses, so that a more complete manifest can be constructed from
them
Improve Rhizome HTTP RESTful interface

Add RHIZOME_BUNDLE_STATUS_READONLY enum value

Tighten up switch statements on bundle and payload status enums (no
default labels)

Rename some recently added enum entries

Return bundle status and payload status in HTTP responses

Add test for failing to decrypt a foreign encrypted bundle payload,
fix bug that caused an assertion failure

Add tests for fetching a non-existent manifest and fetching bundles
whose payload blob is not in the store
Improve MeshMS HTTP RESTful interface

Provide "meshms_status_message" in returned JSON status content
Rhizome Java API: get decrypted payload
Rhizome Java API: negative fetch tests
Rhizome Java API: insert bundle
Rhizome Java API: narrower exceptions