Database schema uses wrong default for reference point

[guntern]

In the agent database schema a wrong format for the reference point is used, which is incompatible with version 2.2.3 of the webclient

https://github.com/helyOSFramework/helyos_core/blob/master/helyos_database/db_schema/0009_agents_table.sql#L47

It should be "front_axle_center" rather than "front-axle-center".