moved CalcLatLong to the grails.plugin.latlongcalc package since the implementation language shouldn't be included, also deleted unnecessary Groovy version
changed min Grails version to 1.3
changed from being a stateful class to a stateless one that returns the 4 computed values in a Map; the return value as a combined string isn't useful in general and is easy constructed by the user; also removed String inputs and conversion to Double since that's easily done in the controller (e.g. "params.lat as Double"). Also added a unit test