dvid-voxels-metadata: Added v0.02 schema file (author: @stephenplaza)
docs: Fix remote repo url for schema subtree.
voxels: Updated to handle v0.02 of the metadata message.
(with changes from @stephenplaza)
Merge latest rev of schema repo into our subtree.
Merge commit 'd007a2bfad80c7b2ce4ad2b88e6ed89f0e1fc565' into schema-change
Merge branch 'schema-change'
tests: Added some debugging code.
VoxelsAccessor: Refactored auto_retry.  Now periodically emits a warning if DVID seems to be taking a long time to respond.