Expansion: Allow max expansion level to be configured per URL

[mcweba]

The gateleen-expansion module provides properties called max.expansion.level.soft and max.expansion.level.hard to configure the global maximum values of expand parameters.

These properties can be used to protect the system from having to process very expensive expansion requests with many levels.

However, there are use cases where a higher expand level than the global level is required. To support these use cases, the global maximum values (defined by the already mentioned properties) should be allowed to be overridden.

Implement the possibility to configure the expand levels on a "per URL basis". This could be done in an additional configuration resource or in the routing rules. When no configuration for an URL is found, the global maximum expand levels should be used.