created table layer_namespace to store the many to many unique mapping of layers and namespaces
changed v1 api to provide a list of namespaces for each layer
changed namespace detector to use all registered detectors to detect namespaces
updated tests for multiple namespaces
Fixes#150
This puts config in its relevant location and moves functions around
loading config files into the main package.
As a side effect of removing cyclic imports for the API config, the
context library is no longer used.
