Add information on wether the projection is global

so that we know if we can wrap the dateline.
ol.Projection now takes a single argument

which is called ol.ProjectionOptions.
ol.Proj4jsProjection_ now takes a single argument
Add configureProj4jsProjection function

so that we can add extent and global parameter to proj4js projections.
And remove setExtent method which is not relevant.
Add test for ol.projection.configureProj4jsProjection
Add global=true for both EPSG:4326 and EPSG:3857
Merge pull request #304 from bbinet/projection-improvements

Some projection improvements