Cassandra-based EquivalenceSummaryStore
Drop String/Content-based methods of LookupWriter for ContentRef-based
Small clean-up in TransitiveLookupWriter
Remove summariesForChildren method

Conflicts:
	src/main/java/org/atlasapi/equiv/CassandraEquivalenceSummaryStore.java
Merge pull request #49 from atlasapi/mbst-2993-stream-equiv

MBST-2993 stream equiv
Remove MongoReplicaSetProbe
ignore cassandra test
Add interfaces for resolving and writing ChannelGroups
Changes to Channels/ChannelGroups persistence, and to related tests.
Of note - channels written to the channels field in ChannelGroups will
be written out as ChannelNumberings with null ChannelNumber, as well as to the existing
channels field
Adapt the persistence layer in light of new temporal fields. Moves some of the linking logic around parent/variation channels, platforms/regions and channelNumberings into the persistence layer from the ingest task. Also reworked the Channel caching layer into separate write-through cache.
Merge branch 'mbst-4019-ingest-pa-channel-data' into stage

Conflicts:
	src/main/java/org/atlasapi/equiv/CassandraEquivalenceSummaryStore.java
	src/main/java/org/atlasapi/persistence/CassandraPersistenceModule.java
	src/main/java/org/atlasapi/persistence/MongoContentPersistenceModule.java
	src/main/java/org/atlasapi/persistence/media/channel/ChannelGroupStore.java
	src/test/java/org/atlasapi/equiv/CassandraEquivalenceSummaryStoreTest.java
Alter spring wiring to use new caching channel store