Create plugin to determine file categories

[johnmhoran]

This plugin will apply a set of rules to certain fields/values collected during a scan (e.g., file_type, mime_type) and add a category (or similarly named) field and associated value (e.g., Java, JavaScript) to the JSON output file.

[pombredanne]

See also #426
I think we could eventually bundle all this as part of the --info scans... this is quite essential
IMHO

[johnmhoran]

👍 @pombredanne See also #1754 Prototype new summary/primary Content Type prototype.