Code review comment for lp://staging/~rvb/launchpad/dsd-api-bug-766158

Several issues as discussed on IRC:

1. There is now a easy-to-fix conflict :)

2. operation_parameters seem to abuse TextLine quite a bit: please use appropriate interface definitions (Choices, Bools, etc) and make sure appropriate enums are exported as well

3. A tiny whitespace issue:

At line 89 of the diff, you've got double space inside a string (at EOL and SOL :):

+ title=_("Only return differences for packages matching this "
+ " name."),