Leaner camus-shopify jar

This PR solves two minor issues:
1) ERROR - SLF4J: Class path contains multiple SLF4J bindings.
2) Some overlapping classes

It does this by excluding explicitly the jars that are causing these problems.
Merge pull request #21 from Shopify/leaner_shaded_jar

Leaner camus-shopify jar
Camus sweeper azkaban job
Shopify job