Add:
    bitshift/crawler/indexer.py
        -Add a `try-except` block to catch the `UnsupportedFileError` exception.

Add:
    bitshift/crawler/indexer.py
        -Add conditional to remove the full path of a repository if the owner's
        directory contains only one sub-directory.

Add:
    bitshift/crawler/indexer.py
        -Add `parse()` and `insert()` calls to `_insert_repository_codelets()`.

Add:
    bitshift/crawler/(__init__, crawl).py
        -Move `__init__.py` to `crawl.py`, and add a `main` block to allow
        running the crawler via `python -m`.