Use lowercase kebab-case formatting for Grails configuration .properties and .yml files

[gsartori]

The suggested case style for configuration properties in Spring is lowercase kebab-case.

A property called my-property in a .yml file will be mapped to myProperty in a @Configuration class by Spring.

Grails is using camelCase for its properties in .yml files.

We should adopt the current standard already supported by Spring for Grails configuration properties.