Handle composite row keys in a nice way

[rzvoncek]

Composite row keys currently have to be built like this:
CQLRecord.create(
CompositeType.build(
ByteBufferUtil.bytes("metric"),
ByteBufferUtil.bytes("country"),
ByteBufferUtil.bytes(1234L)), // this is the row key
Lists.newArrayList("metric2", "country2", 1234L, 1.0d, "uri") // this is a column
);

This is not very pretty (and definitely not quite intuitive) from the user point of view and can be improved.