Ensure OAuth support doesn't pass secrets in URL but in x-www-form-urlencoded Body

[vorburger]

@Grandolf49 make sure that https://github.com/openMF/fineract-client/blob/767943e88793350fd6b0e36dd8d370e541a54995/src/main/java/org/mifos/fineract/FineractApiClient.java OAuth support doesn't pass secrets in URL but in x-www-form-urlencoded Body, see https://issues.apache.org/jira/browse/FINERACT-1145 for https://issues.apache.org/jira/browse/FINERACT-629.

[vorburger]

https://github.com/apache/fineract/pull/1320/files probably illustrates best what actually needs to be changed how (I understand this proejct doesn't use JQuery to invoke the REST API, but you get the idea and should be able to do the equivalent).

[Grandolf49]

Thanks @vorburger I'll look into it