Options for better cube metadata

[mountainMath]

The current implementation of get_cansim_cube_metadata only shows overview information, but the metadata provided covers the entire metadata for the table. The parsing of the metadata should be expanded to include the entire metadata and provide an alternative way to access cube metadata and make it available without having to download the entire table.

This would be useful to explore the metadata without downloading the table first, and also provide a way to add metadata to tables generated via get_cansim_vector.