Rasterstats

- Use GetNextFeature to iterate over OGR layers

- Added a `percentile_q` statistic to calculate the qth percentile for each feature.
- Removed undocumented rasterstats script (may be replaced with more robust CLI tool by 1.0)
- Optional support for outputing "mini-rasters": the clipped, masked numpy array for each feature. (thanks to ozak again!)
- Support for dynamically adding third-party stats functions - which take a masked array and return a scalar value. (thanks to ozak)
- Additional examples and ipython notebooks in docs

- new method for clipping to raster extents, changes bbox_to_pixel_offsets to fix src_array edge cases (thanks allhailwesttexas and timcera)

- Added examples directory with ipython notebooks
- proper pip requirements files
- Deprecated `raster_stats` in favor of `zonal_stats`
- Support for GeoJSON-like FeatureCollections (any things that implements FeatureCollections in the __geo_interface__)
- Support for in-memory numpy arrays and geopandas dataframes

- Add optional "all_touched" rasterization strategy whereby all pixels that touch a geometry are considered (thanks ozak)

- Gaurd against touching (but not overlapping) polygons. Fixes 27... thanks engelmannjens