Compatibility with CordappContext.config

[manosbatsis]

ConfigurationService and ConfigUtils should use CordappContext.config as described in CorDapp configuration files, or at least provide compatibility with the convention.

The current implementation is incompatible with cordapp configuration hooks available, e.g. in the Cordform gradle task, or the TestCordapp.withConfig used with MockNetwork.

Even a minimal change such as updating the target file names according to the convention might just work, e.g. "membership-service-2.0.conf" VS "membership-service.conf"