CORE-5832 Removed Metadactyl Java references.

Updated endpoints that called Metadactyl java classes to temporarily throw an exception until reimplemented in clojure.
Removed the metadactyl.metadactyl namespace, which mainly contained functions that called into Metadactyl Java classes.
Refactored metadactyl.metadactyl user functions and macros into metadactyl.user namespace.
Removed metadactyl, c3p0, and spring dependencies.