PickleShare - a small 'shelve' like datastore with concurrency support

Like shelve, a PickleShareDB object acts like a normal dictionary.
Unlike shelve, many processes can access the database simultaneously.
Changing a value in database is immediately visible to other processes
accessing the same database.

Concurrency is possible because the values are stored in separate files.
Hence the 'database' is a directory where all files are governed by
PickleShare.

1. build dependencies:
   1. python3-module-setuptools
   2. rpm-build-python3
   3. python3(pytest)
   4. python3(tox)
   5. python3(tox_console_scripts)