Pyserval

Pyserval now checks the return code of all server replies

Implemented missing endpoints

- [route](https://github.com/servalproject/serval-dna/blob/development/doc/REST-API-Route.md)
- [rhizome newsince](https://github.com/servalproject/serval-dna/blob/development/doc/REST-API-Rhizome.mdget-restfulrhizomenewsincetokenbundlelistjson)
- [meshms newsince](https://github.com/servalproject/serval-dna/blob/development/doc/REST-API-MeshMS.mdget-restfulmeshmssendersidrecipientsidnewsincetokenmessagelistjson)

With these additions, all REST-functionarly should now be supported.

More convenient high level interface for MeshMS and MeshMB

Plenty of bugfixes.

Especially related to custom manifest fields.

* Rewrite Journal interface to be in line with Bundle interface
* Miscellaneous fixes

Implemented error handling for bundle creation/insertion (not implemented for journals yet, though)