Exclude non-release artifacts from the classpath for dependent projects in a box

[pmbauer]

Scenario:
Project B depends on A.
A and B are in a box.
A has non-release artifacts (e.g. test) and dependencies (:dev profile).

Currently:
box (via lein checkouts) adds non-release artifacts of A to B's classpath, but not non-release dependencies. For example, tests from A are added to B's classpath but test dependencies defined in A's test profiles are not.

Proposed Mitigation:
box only adds release artifacts of A (e.g. src-paths) to B's classpath, ignoring tests and other dev dependencies.