Merge pull request #311 from gavincornwell/1.4-dev

MOBSDK-741: ConfigService implementation - evaluators and corresponding tests
Merge pull request #312 from gavincornwell/1.4-dev

MOBSDK-741: ConfigService implementation - added empty and invalid config tests
Merge pull request #313 from gavincornwell/1.4-dev

MOBSDK-741: ConfigService implementation