Lookup value is null if classpath contains multiple ResourceProviders which canProvide lookup

Issue Overview
Currently ArquillianResourceTestEnricher is doing lookup for first provider from the classpath which can provide lookup. You can check code [here](https://github.com/arquillian/arquillian-core/blob/master/test/impl-base/src/main/java/org/jboss/arquillian/test/impl/enricher/resource/ArquillianResourceTestEnricher.java#L107)

If classpath contains multiple providers which can provide lookup, then it's returning first provider lookup which is resolving using ArquillianResourceTestEnricher.

Expected Behaviour
Arquillian should take Provider which has higher priority among all providers which canProvide lookup.
Or it should lookup at least all provider and return first non-null value.

Current Behaviour
It's providing first provider's lookup which may be null.