Use standard abc module to enforce overriding of abstract methods

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Re-organize database testing code

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Implement functions to retrieve data from db for upload

These retrieve a whole slew of historic data, aggregated across a system.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Fix bug in system timezone handling

We need to instantiate tzlocal in the default case.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Start on a simpler upload implementation

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Remove unused exception class MockError

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Refactor pvoutputorg date/time parse and format routines

Also add test code for them.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>