#414 Load custom logger via SPI

...rc/main/java/fitconnect/api/domain/metadata/Metadata.java

...c/main/java/fitconnect/api/domain/metadata/data/Data.java

.../main/java/fitconnect/api/domain/submission/Callback.java

...in/java/fitconnect/api/domain/submission/ServiceType.java

...ain/java/fitconnect/api/domain/submission/Submission.java

api/src/main/java/fitconnect/api/logger/LoggingProvider.java

.../src/main/java/de/fitconnect/client/FitConnectClient.java

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

impl/src/main/java/fitconnect/impl/SubmissionSender.java

impl/src/main/java/fitconnect/impl/SubmissionSubscriber.java

.../src/main/java/fitconnect/impl/auth/FitCoAuthService.java

...n/java/fitconnect/impl/logger/DefaultLoggingProvider.java

impl/src/main/java/fitconnect/impl/logger/SdkLogger.java

...s/META-INF/services/fitconnect.api.logger.LoggingProvider

.../java/fitconnect/impl/auth/OAuthTokenIntegrationTest.java