Overriding some properties does not work

[gosuvigi]

When you want to override some of the wro4j properties in the Spring application.properties file, for example, some of them cannot be overridden, e.g. 'cacheUpdatePeriod'.

The problem lies in the Wro4jConfig class, inside the wroFilterProperties() method where all the keys that are put in the Properties objects should be Strings and not ConfigConstants enumeration values.

Also, maybe all the properties in ConfigConstants should have a corresponding property inside your Wro4jProperties class.