SERVER-12175 Add 2dsphere index option "2dsphereIndexVersion"

- Defines version 1 and 2; both are supported.
- Indexes without this option are assumed to be version 1.
- New builds get version 2 (if version unspecified).
- Version 1 throws in getKeys if the geometry is one of the types
  introduced since 2.4.0 (MultiPoint, MultiLineString, MultiPolygon,
  GeometryCollection).