Merge Conflict Resolution; Added Suites to run_tests.py

Note the REPEAT_INDEXER_SUITE doesn't yet exist in the tree.
Revise IndexedPiece Tests for Metadata

- Test setting a valid field
- Test setting an invalid field
- Update doctest in IndexedPiece.metadata() so it uses a valid field
Revert Part of "fixing more pylint issues"

This reverts part of commit bab21ffb9e13bd5761806839f3af7c1e577056ff.

I just wanted models/aggregated_pieces.py and its entry in __init__.py