Breaking change introduced in 3.1.0 -> ~3.2.0

[bcomnes]

In https://github.com/maxogden/abstract-blob-store/pull/31/files#diff-f763f1634ff40f723dd8de924120ce55R60 a new test was added to check for the presence of err.notFound on blobs that aren't found and released as semver minor. I believe this to be a semver mistake, as its breaking downstream blob store tests in non-breaking semver ranges.

What should be done:

• Skip the t.ok(e.notFound, 'error reports not found') test and release as a patch release in 3.0.0 major family.
• Document the error.notFound = true property in the spec and re-add the test and release as 4.0.0 with release notes regarding the change.

[bcomnes]

Ok, the immediate issue is fixed #40

The test suite is no longer breaking due to the test of a previously unspecified error properties.

The next question is, do we spec that and include it in a major revision. This kind of thing seems like it may be the concern of the concrete implementations.