WIP plugins ...

* defn- -> defn
* test for 'jars-in-dir'
* move CLI arg test to core_test
cleanup
move should-process? into let block
WIP plugins ...

* cleanup import
* rename / doc process-file and process-container
rename variables for clarity
final(???) cleanup pass on plugins ns
test plugin service
fixup
add logging
exclude servlet API from jetty

It is already in the dep tree elsewhere, and the duplicate detector
found duplicate classes on the classpath.
fix duplicate detection, tests, fix file/jar handling
fixup
moving tests around and stuff
rename plugin test .jar
cleanup