Support multiple war-resources-paths

We currently support multiple resource-paths by doing (concat (:resources-path project)). We support the same for source-paths. It would be super useful to also support multiple war-resources-paths in the same way (so that multiple activated profiles can bring in different sets of war-resources composably).

My use case currently is that I have one set of war-resources that need to be brought in conditionally based on a profile-activated choice of authentication strategy (legacy J2EE authentication or not), and one set that needs to be brought in based on choice of JBoss version. Right now I've got to maintain m*n sets of resources where I could be maintaining m+n with this option.

Patch: Allows support for multiple war-resource-paths via the same mechanism used for resource-paths. Only difference is that this was pulled out into a separate function for uberjar's use, so instead of (doseq :when) we need to use (filter identity) to avoid duplicating the (doseq :when) logic.