Quick fix for JSON root setting in CustomMethods

This is probably not a proper and complete fix, but the gist is that
support for the include_root_in_json settings are handled in Base when
they ought to be considered in the Format classes as well.
CustomMethods knows nothing about the config handling done in Base so
it's stuck with the unconfigurable default before this change.
Merge branch 'custommethods-root-quickfix' into integration

* custommethods-root-quickfix:
  Quick fix for JSON root setting in CustomMethods