Add dependency on commons-lang3.

Adds Maven dependency on `commons-lang3`.

Apparently this dependency was available through a transitive dependency, and some Marketplace-and-related code is already trying to use Commons Lang 3, but it wasn't actually a dependency in uPortal.  This change makes it one.

Does not disrupt commons-lang 2
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`commons-lang3` uses a different package than does old `commons-lang` (2), such that adding lang3 doesn't disrupt dependency on and usage of lang2.  Isn't that nice? :)

Deferred work: 
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* upgrade existing Commons Lang (2) usages to Commons Lang 3 so we can drop dependency on Commons Lang 2.