Ecoshard

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* Added a new command line mode –reduce_factor that reduces the number of pixels
in a raster by that integer amount. Ex:

``python -m ecoshard base.tif --reduce_factor 4 max target.tif``

this call makes the size of the pixels in base.tif 4 times larger on the
edge, thus reducing the total size of the image by 16 times, the convolution
upsample is done with a "max" and the output file is ``target.tif``. The
modes "min", "max", "sum", "average", "mode" are available.

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* Added a ``download_url`` function to ``ecoshard`` to fetch files via
http(s).
* Developing Flask module to visualize ecoshards.

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* Hotfix: gs to gsutil for copying to buckets.

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* Added functionality to download a url.
* Added functionality to copy to a google bucket.
* Fixed an issue on functions that should write a token file but didn't.

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* Added a ``--force`` flag to the command line utility.

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* Initial release.