Add option to drop the caching tables from the database and exit
Summary:
This can be used to enforce the regeneration of the caching tables with the latest database schema - for instance, by the package manager when upgrading the PyKolab package.
This patch complements D587 in an attempt to fix T2274.
Reviewers: PyKolab Developers
Maniphest Tasks: T2274
Differential Revision: https://git.kolab.org/D593