Support Multiples Atomspaces

[MarcosPividori]

Now:

  main = runOnNewAtomSpace $ do 
                               asAddNode  (Node ....)
                               asAddLink  (Link ....)

With multiples atomspaces:

  main = do
           a1  <-  createAtomSpace
           a2  <-  createAtomSpace
           addNode a1 (Node ...)
           addNode a2 (Node ...)
           ....

I plan to offer both options. As it is more common to work with only one atomspace, the first approach is far more confortable because you avoid passing the atomspace instance as an argument each time for each action.

[MarcosPividori]

done after: https://github.com/opencog/atomspace/pull/222