stubbed out first IChannel implementation

* Created initial `IChannel` implementation; still stubbing out
interfaces.
* Removed NET35 and NET40 projects. Will re-add them once files stopped
being added / moved / renamed.
* Renamed `IConnectionConfig` to `IHeliosConfig` - going to reuse this
class in a few areas in the namespace.
* Moved `IHeliosConfig` to the root `Helios.` namespace.