fix attachProtoDeep for setModuleDefaults
fix attachProtoDeep for setModuleDefaults

setModuleDefaults wouldn't apply the config prototype functions (like `.get()`) to the modules config in the case that no other configuration was provided for this module.  
Also resetting the `checkMutability` flag according to initParam `ALLOW_CONFIG_MUTATIONS`, since the setModuleDefaults function could have been called after the first config.get and then would expose the defaults mutable.
joshparolin/node-config,eloquence/node-config