Update JackonAutoConfiguration to apply all http.mappers properties

Previously, only the http.mappers.json-sort-keys property was applied
by JacksonAutoConfiguration. This commit updates it to also apply the
http.mappers.json-pretty-print property as well.

See #1919
Test that http.mappers props are applied by JacksonAutoConfiguration

Closes gh-1919
Merge branch 'gh-1919' into 1.1.x