SequenceDictionary adds containsRefName, updates recordName key types.

Added containsRefName to SequenceDictionary, allowing us to check whether a SequenceDictionary object contains a particular sequence.
SequenceDictionary recordNames keys should be Strings (they had been Avro Utf8 objects, which was messing up lookups into the map itself from Strings).
Added AdamContext.referenceLengthFromCigar
Convenience method to create a projection from an Iterable[FieldValue].
Added the TrackedLayout class.
Added filterByOverlappingRegion to AdamRDDFunctions
Added the VizReads tool to CLI.

VizReads is a tool for interactive or static visualization of aligned reads along the genome.