Disabled AllDemographics due to Apsis exception

When enabling, the server will return an "A fatal internal error
occured, please contact support".

For now we will need to be handling it this way instead, until we get
feedback from Apsis support.
Finalized subscribers implementation

Due to the previous mentioned exception, the implementation was missing.
This solves the case.
Handled leading slash in path sending to http2

When urls returned from Apsis queueing system, the path will include a
leading slash.

This conflicts with http2, as it always prefixes the specified urls with
slash, and this ends up sending double slashes in the urls - which leads
into the classical "A fatal internal error occured, please contact
support" exception.
Refactored specs for better support single tests

This will improve support for testing a single test at a time.

Additional refactoring will be needed to be fully optimal, but this is a
big step on the way.