Add the ability to specify file output options

[GreatEmerald]

At the moment processLandsat allows only setting the extension of the file output. However, for each file driver, GDAL has a large amount of options. For instance, I can get a 30% reduction in file size and some speed up in processing time if I use GeoTIFF as output and the creation options COMPRESS=DEFLATE ZLEVEL=9 NUM_THREADS=4 SPARSE_OK=TRUE. It would be nice if there was a way to pass these options (usually they are passed to writeRaster()), so that an extra recompression step would not be necessary.

[loicdtx]

Thanks for the suggestion. That sounds feasible, I'll look into it soon.