Upgrade to radicale 2

Radicale 2 has different configuration and database layout than Radicale. Debian package does not automatically upgrade the configuration or database. The following tasks are pending for a smooth upgrade:

• Merge !1389 (closed). This will ensure that starting fresh, radicale1 and radicale2 will work.
• Consider using uwsgi. This seems to be the preferred way for radicale2. Write migration code.
• Upgrade path from radicale1 configuration to radicale2 configuration.
• Migrate database of radicale1 to radicale2.
• Update diagnostics and firewall ports for uwsgi.
• Add link to web interface.
• Update manual page.