Improvements

Bugfixes and code tidy:-
Support a 'downloaded' flag in the DB for media.
Improved tests and logging
Switch to using ThreadPoolExecutor and Futures for parallel downloads
Add a bad IDs YAML file for broken IDs (workaround to Google issue)
Fix support for Raspberry Pi Zero
Added Codacy, code quality checks

New Google Photos Library API update

Now uses the new API instead of attempting to combine the picasa and drive APIs.

It uses parallel processing for fast downloads.

cron capable version

Now fit for running in the background with cron.
Fast indexing when no changes have occurred.
Exits cleanly on sigterm
Single instance only allowed for each root folder (further instances exit with a message and no error).
Fixes for #16 #11 #17 #15 #14 #7

Bug Fixes

Fix version in setup
Fix Issues #6 #9
Fix root id retrieval (described in #5)
Add python logging.

Initial working version

From this point onwards it is intended that updates to the code will be compatible with previous releases such that users will be able to continue to incrementally synchronize their photo stores to existing local folders.

(re-indexing due to new db schemas is to be expected)