Use loggers instead of println commands in dhis connector service

In DHIS connector service class there is a few `system.out.println()` commands that need to be replaced with loggers. 

• https://github.com/openmrs/openmrs-module-dhisconnector/blob/0c5253553fd7c472c8da74a0cb1edb37b441eb52/api/src/main/java/org/openmrs/module/dhisconnector/api/impl/DHISConnectorServiceImpl.java#L228
• https://github.com/openmrs/openmrs-module-dhisconnector/blob/0c5253553fd7c472c8da74a0cb1edb37b441eb52/api/src/main/java/org/openmrs/module/dhisconnector/api/impl/DHISConnectorServiceImpl.java#L245
• https://github.com/openmrs/openmrs-module-dhisconnector/blob/0c5253553fd7c472c8da74a0cb1edb37b441eb52/api/src/main/java/org/openmrs/module/dhisconnector/api/impl/DHISConnectorServiceImpl.java#L257
• https://github.com/openmrs/openmrs-module-dhisconnector/blob/0c5253553fd7c472c8da74a0cb1edb37b441eb52/api/src/main/java/org/openmrs/module/dhisconnector/api/impl/DHISConnectorServiceImpl.java#L582
• https://github.com/openmrs/openmrs-module-dhisconnector/blob/0c5253553fd7c472c8da74a0cb1edb37b441eb52/api/src/main/java/org/openmrs/module/dhisconnector/api/impl/DHISConnectorServiceImpl.java#L801
• https://github.com/openmrs/openmrs-module-dhisconnector/blob/0c5253553fd7c472c8da74a0cb1edb37b441eb52/api/src/main/java/org/openmrs/module/dhisconnector/api/impl/DHISConnectorServiceImpl.java#L822
• https://github.com/openmrs/openmrs-module-dhisconnector/blob/0c5253553fd7c472c8da74a0cb1edb37b441eb52/api/src/main/java/org/openmrs/module/dhisconnector/api/impl/DHISConnectorServiceImpl.java#L1077
• https://github.com/openmrs/openmrs-module-dhisconnector/blob/0c5253553fd7c472c8da74a0cb1edb37b441eb52/api/src/main/java/org/openmrs/module/dhisconnector/api/impl/DHISConnectorServiceImpl.java#L1104

Note: There could be more, please search for error stack trace prints and normal system outs both.