For me, Brad Parks answer did not work in Eclipse Luna (4.4.2), that is, adding web application libraries did not have any effect .. that remained empty.
I needed to configure the web deployment assembly . My library was in WEB-INF, which again looked like /{project}/web/WEB-INF/lib
, and when I added the deployment assembly , as shown below,

Then under these two I had an entry for each jar from the {project}/web/WEB-INF/lib
with Deploy Path as WEB-INF/lib
.
This deployment assembly automatically populated my Web App Libraries
.
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