Add parent and variations fields to Channel
Added Platform and Region as separate classes extending ChannelGroup, rather than typed instances of ChannelGroup
Remove ChannelGroupType from ChannelGroup
Add ChannelNumbering, which links a Channel to a ChannelGroup via a channel number.
Also added references to ChannelNumberings into Channel, so can find a Channel's numbers from the Channel object
Change references to Channels/ChannelGroups to Longs. Add ChannelGroupType, which is an Enum of the types of ChannelGroup, purely for persistence.
Correct equals() implementation for ChannelNumbering
Add start/endDates to image and title fields for Channel/ChannelGroup, as well as to
Channels and ChannelNumberings. Adjust simple model to output new fields.
Change 'channels' field to 'channelGroups' to more properly reflect its contents
Alter name of channelGroup list from 'channels' to 'channelGroups'
Add new regional/timeshift fields to Channel for additional variant info from the PA.
Add helper method related to countries to ChannelGroup.
Rework history output for simple model, and tidy up Simplification
 - Change channelNumber param to String
 - Add new ordering for channelNumbers. Ordered with non-zero prepended strings ordered in numerical order, followed by zero prepended strings, ordered in numerical order
Refactor of simple model around channels. Ordering for simple-model channel numberings moved to separate class.
Test added around ordering.
Modify equals method on ChannelNumberings
Minor tweaks to channels model after refactor of persistence layer
Merge pull request #91 from atlasapi/mbst-4019-ingest-pa-channel-data

Ingest Channels from PA