0.14

Changes in 0.14

• Improved error messages when data cannot be accessed from opendap
• added caching of chunks using a Least-Recently-Used-Cache
  Cache Size in MB can be set for the store using the newly added parameter cache_size
• avoid concurrent calls of the same request
• Ensure classes SessionExecutor and CciOdp can be serialised and de-serialised.
  This is necessary for support of dask clusters.
• Updated list of data states