callService shouldn't need a previous established connection to call services

[hughjfchen]

Currently, before you can use callService/callService' to call services on other nodes, you must use connection, listen or initNode established some connection state. This restrict should be removed because callService/callService' know how to connect to the node where the services it wants to call located.

[agocorona]

in the meantime, runCloud callService... work fine to call services under the TranIO monad.

callService is asynchronous, so it will execute alternative computations. If that is not desired, use sync . runCloud $ callservice..