Global keystore.db

keystore.db is currently located in ```$PWD```. It is little bit awkward for CLIs.

Boto uses AWS CLI configurations located in ```~/.aws/```, and it is overridable.
Link: https://boto3.amazonaws.com/v1/documentation/api/latest/guide/quickstart.html

Git config also has a good convention. It uses several configuration files, from repository local to user global, and system-wise.
Link: https://git-scm.com/docs/git-config#FILES