Bump dependency versions

Upgrades dependencies. Upgrading Spring caused two significant changes:

Content-Encoding and ETag headers to be incompatible. Implemented X-Return-Etag header that is used to specify an ETag should be returned, otherwise Content-Encoding: gzip is returned, if appropriate to the type of request. This lead to increased compression being enabled by default, rather than requiring a configuration parameter, and improving integration tests to check for ETag and Content-Encoding when appropriate.
A new gradle version, which changed how test coverage had to be reported.

There were also some formatting changes to allow the local ./gradlew build to pass the checkstyle test.

zowe / data-sets