Add root logging configuration and improve format

Ghost User
2019-11-13T22:00:53+01:00

Previously no loggers were enabled that concrexit uses. This means that
all logs by concrexit code were ignored in production. This commit adds
a root logger that will make sure all logs by concrexit and imported
packages are logged to the log file.

This commit also improves the 'verbose' logging format, which previously
contained unneeded information and less specific information on which
package was doing the logging.

Closes #956 and #957