Fix: reduce dev mode output

[stuartherbert]

To make the output easier to read, we need to reduce the amount of it.

• No longer display the value when we store/retrieve from the checkpoint
• No longer display HTTP responses
• Make the output more diff friendly by switching to relative timestamps rather than absolute ones (or at least make it an option)

Do we want to write the suppressed data into a machine-readable file via the output plugins?

[stuartherbert]

Definitely still want to switch to relative timestamps for the output messages.

Not sure the other items are needed, as SP 2.0.0 truncates output written to the logs unless --verbose is used.