core: tests around the environment setup_version
core: use a Monitor in BoxCollection
core: upgrade to v1.5 box dir format if it can
core: error if newer home dir version is detected
core: BoxCollection#all returns versions
core: BoxCollection can find with version constraints
core: all box collection tests pass
core: Box has a version field
core: boxcollection test tests versions
core: environment tests pass
commands/box: list works with the new versions
core: BoxMetadata can read the JSON description
commands/box: broken box adding, but more options/tests
core: can add/search boxes with slashes in name
core: BoxAdd can add from metadata, version constraints, more
core: BoxMetadata#version can constrain by providers
core: BoxAdd adds matching provider even if lower version
core: more output for box adding
core: delete the temporary file if adding succeeds
core: add newline to end of download if windows