Added 'requirejs' property to POM as required by the latest webjars-locator

The latest _webjars-locator_ library seems to look in every `pom.xml` for this property, and mangles the second part to point to the actual location of URI.js.

For example, it should produce a config like this (after mangling):

    {"paths":{"URI.js":["/webjars/URI.js/1.12.0/URI.js","URI.js"]}

Before this change, _webjars-locator_ simply skipped over this module (no config was generated).