feat(coloctapp): implement cleanup_content

[grossir]

Helps solve:

• https://github.com/freelawproject/juriscraper/issues/1215
• freelawproject/courtlistener#1094

Implement cleanup_content, only for coloctapp:

• to remove tags with tokens that changed every scrape, altering the hash and causing duplicates
• to remove classes that conflicted with CL classes and messed up the diplay

[grossir]

To test this you will need to copy paste

import hashlib

def sha1(s):
    """Return the sha1sum of a string.

    !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
    ! This algorithm is obsolete for most purposes. Its !
    ! usage is discouraged. Please use SHA256 instead.  !
    !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

    :param s: The data to hash. Ideally bytes, but if unicode is passed in, it
    will convert it to bytes first.
    :return: a hexadecimal SHA1 hash of the data
    """
    if isinstance(s, str):
        s = s.encode()
    sha1sum = hashlib.sha1()
    sha1sum.update(s)
    return sha1sum.hexdigest()

And then call it where appropiate in the sample_caller

        # cleanup_content is called before the extraction task in CL
        # so it is only useful for cleaning HTML files
        data = site.cleanup_content(data)
        logger.info(sha1(data))

Perhaps we should add this to the sample_caller...