Issue #984 - Adding o.m.c.NaturalEarth.test plugin

The PR includes:

- fixing build (the o.m.c.NaturalEarth plugin)
- adding o.m.c.NaturalEarth.test plugin
- adding ShapeFileTests

The test uses ShapeFile against ne_50m_coastline.shp (50m_physical naturalearth) dataset, verify and read the shapefile.