Errors, errors everywhere (but not necessarily my errors)

Fixes

• Issue #1: Avoid removing the unit of work twice when an error during the CommitAsync happens

Concurrency always causes problems (part 1?)

Fixes a concurrency issue with repository creation, initialization and transaction.

Some libraries try to parallelize operations and if those operations create a "unit-of-work" it might cause race conditions during the unit-of-work initialization.

Disable automatic SaveChanges if not configured

This is a fix release for v0.2.0

Dont't flush by default

Previously, a SaveChanges was always called whenever a unit of work was disposed. This was changed to avoid unnecessary to SaveChanges even when only the database was queried.

First release

This is the first release of a scoped/nested unit-of-work implementation.