Landsat landcover rasters for `2015` and landcover change for `2010-2015` to be added

[kasra-keshavarz]

Th landcover dataset is in 30m resolution and could be found in the following:

1. Landsat landcover 2015: http://www.cec.org/north-american-environmental-atlas/land-cover-30m-2015-landsat-and-rapideye/
2. Landsat landcover change from 2010 to 2015: http://www.cec.org/north-american-environmental-atlas/land-cover-change-30m-2010-2015-landsat/

[kasra-keshavarz]

Solved with #21