Change PA image prefix to new base URL, remove legacy base URL
Merge pull request #434 from atlasapi/pa-image-prefix

Change PA image prefix to new base URL, remove legacy base URL
Schedule ITV equivalence task to run daily
Split C4 platforms into separate sources

The data and hierarchies are sufficiently different between
C4 platforms that the content needs to be separated into
different sources in Atlas for each C4 platform.
Merge branch 'c4-p06-separate-source' into stage