Trigger a render in ol.Control#setMap

Closes #1525
Merge pull request #1599 from fredj/1525

Trigger a render when a control is added to the map
Add new 'accuracyGeometry' property to ol.Geolocation
Add new 'positionGeometry' property to ol.Geolocation
Use accuracyGeometry and positionGeometry in geolocation example
Better ol.Geolocation documentation