Modify offline mode to include caching on server connection failure

[kzscisoft]

This will likely require a complete refactor of offline mode. We want to now include caching of objects such that if a connection cannot be made to the server, these objects are uploaded at a later time. This can be merged with the offline mode concept, the difference being offline mode would be clearly stating that connection to a server is not possible, whereas a typical run would keep re-trying to upload the runs at a given interval.

This could be merged with the concept of having object orientation for Simvue objects and their storage locally.