Add support for migrating legacy categories and concepts from 1.x

There may not be any more apps using Avocado 1.x, but for completeness
this should cover the remaining migration.
Rename data subcommand update_data_version => incr_version

This makes it a bit more clear than simply 'update'.
Fix missed update from property => method since 2.0.x
Remove requirement in DataFieldCommand to pass labels

The behavior is now (naturally) defaults to all datafields
Expose cache_key on wrapped cached methods
Determine CACHE_METHODS dynamically, print total time for cache
Remove filtering of non-enumerable fields for cached computed values

The cache subcommand should be 'dumb' when it comes to caching. The
upstream implementation of the methods should handle how and what will
be cached by the method's return value.
Remove DataView.count field

This field was not used, nor does it make sense since a view represents
the retrieved fields and ordering.
Register Data- View, Context, and Query with admin

This is merely convenience for debugging and support.
Fix plural form of DataQuery label