XGboost Changes for ocean-prefilter

[Emerald-Z]

Main contributions:

• rewriting of the classification logic to use xgboost instead of histogram comparison
• update of the README to be consistent with changes
• adding test files to test the new logic
• making the camera_name an optional parameter

[bhaney]

Nice first pass on adding xgboost to this package, I think it'll be the way going forward! I have comments on writing tests, and I would also recomment running the linter too so that it catches any style issues in the source code

[bhaney]

Thanks for the edits! Here are a few more small corrections to do

[bhaney]

LGTM!