BUG/API: info repr should honor display.max_info_columns
Closes https://github.com/pydata/pandas/issues/6939

I think this is what we agreed on. The tests are split up. In `test_format` we do more of the following global settings tests. The rest are in `test_frame` which directly call `df.info()` and I'm basically testing that the kwargs there override the global settings.

I guess this only closes half of https://github.com/pydata/pandas/issues/6939, There's still the second bullet:

> we could add a keyword argument like show_counts (or another name) to specify if you want to show the non-null counts (to be able to override the max_info_rows option for a specific info call)
 let's create a new issue for `show_counts` and put in 0.14.1

but this IS an API change yes? as `max_info_columns` took an integer before, and now is boolean/None ?
 I didn't change anything with the config. The only API change was to `info` where now the `verbose` kwarg take None/True/False.

the `max_info_columns` is the same as before, but now `info` actually follows it (unless overridden). I do remember a discussion about what to do with `None` in this kind of setting, but I don't think it was for this issue.
 @TomAugspurger sorry...you are right....was thinking about something else....ok...gr8 then....

merge when ready / green

(and I would separate out the `show_counts` option to another issue for later)
 Ok. I'll open one up. The test failure was a mistake in the test. Should pass now.
 excellent!
