#414 Rename impl module to core,

...ko/fitconnect/api/domain/model/submission/Submission.java

client/src/main/java/de/fitko/fitconnect/TestRunner.java

...c/main/java/de/fitko/fitconnect/client/ClientFactory.java

...t/src/main/java/de/fitko/fitconnect/client/di/Client.java

...ava/de/fitko/fitconnect/client/di/FluentSenderClient.java

core/README.md

core/pom.xml

.../main/java/de/fitko/fitconnect/core/SubmissionSender.java

...va/de/fitko/fitconnect/core/auth/DefaultOAuthService.java

...c/main/java/de/fitko/fitconnect/core/crypto/HashUtil.java

...ava/de/fitko/fitconnect/core/crypto/JWECryptoService.java

.../main/java/de/fitko/fitconnect/core/http/ProxyConfig.java

...java/de/fitko/fitconnect/core/http/ProxyRestTemplate.java

...tko/fitconnect/core/http/X509CRLHttpMessageConverter.java

.../fitko/fitconnect/core/logger/DefaultLoggingProvider.java

.../main/java/de/fitko/fitconnect/core/logger/SdkLogger.java

...fitko/fitconnect/core/metadata/MetadataUploadService.java

...ava/de/fitko/fitconnect/core/validation/KeyValidator.java

...tconnect/core/validation/MetadataSubmissionValidator.java

...F/services/de.fitko.fitconnect.api.logger.LoggingProvider