Add:
    bitshift/crawler/(__init__, crawler, indexer).py
        -add `logging` module to all `bitshift.crawler` modules, for some basic
        diagnostic output.

Add:
    bitshift/crawler/indexer.py
        -add _debug().
        -add content to the module docstring; add documentation to GitIndexer,
        and the functions that were lacking it.
        -add another perl one-liner to supplement the `git clone` subprocess
        call, which terminates it after a set amount of time (should it have
        frozen) -- fixes a major bug that caused the entire indexer to hang.

Add, Fix:
    bitshift/crawler/
        __init__.py
            -add module and crawl() docstrings.
            -add repository_queue size limit.

        crawler.py
            -account for time spent executing an API query in the run() loop
            sleep() interval.

Additions are not tested and not yet documented.

Add:
    crawler.py
        -add threaded GitHubCrawler class, which interacts with a GitIndexer
        via a Queue.

    git_indexer.py
        -add threaded GitIndexer class, which interacts with GitHubCrawler via
        a Queue.
        -rename context-manager ChangeDir class to _ChangeDir, because it's
        essentially "private".

    __init__.py
        -add body to crawl(), which creates instances of GitHubCrawler and
        GitIndexer and starts them.

Add:
    bitshift/codelet.py
        -add name field to Codelet.

    bitshift/crawler/crawler.py
        -fix previously defunct code (which was committed at a point of
        incompletion) -- incorrect dictionary keys, etc..
        -reformat some function calls' argument alignment to fit PEP standards.

    bitshift/crawler.py
        -add sleep() to ensure that an API query is made at regular intervals
        (determined by the GitHub API limit).