User-configurable deletions for content normalization

[ryanfb]

It might be nice for users to be able to put an array of strings or regexes in config.yaml that can be used to normalize content before diffing.

For example, I could put 'Scroll down for video' in for deletion for dailymail_diff, or with regexes globemail_diff might be able to remove stock price changes.

Related to #10, there might be a tradeoff for where to put such an array in the YAML hierarchy. Putting it as a top-level key would mean less repetition for people using one config per news source, putting it as a key under each feed would allow people using one config for multiple news sources to have different ones for each.

See also: #14

[ruebot]

Happens a lot for hockey scores on CBC and La Presse 😄

Might kinda be related to #7 too? Or that just might be TorStar's wretched "digital platform".

[edsu]

I had to disable breitbart_diff because diffengine went crazy tweeting when they removed their email subscription link from the body of the story. So this is kind of an important feature to add.

[ruebot]

Yeah, canadaland_diff did something similar to that recently, and I have a lot of false positives.