* Add README.md to tests/ to describe test structure and pytest customizations
* Add package-level docstrings to backends
* Add README.md explaining the backend architecture
* Small improvements to docstrings in backend modules
* Restructure the backend automodule docs
* Add more docstrings to backend connections
* Add init to base backend Connection class to document expected interface
* Reword the backend/README.md docs
* add timestamp to transaction assignment
* add reassignment delay to configuration
* refactor to multipipes
* # This is a combination of 7 commits.
# The first commit's message is:
stale transaction monitor and tests
# The 2nd commit message will be skipped:
# simplify logic
# The 3rd commit message will be skipped:
# node will assign to self
# The 4th commit message will be skipped:
# block listens for insert and update
# The 5th commit message will be skipped:
# more test coverage
# The 6th commit message will be skipped:
# test coverage
# The 7th commit message will be skipped:
# test coverage
* stale transaction monitor and tests
* update operation only returns new value
