Use integer 200, not binary for log test data

wm uses integers for reponse codes so this makes for a more accurate
test
Compatibility fix for webmachine 1.10.5

In 1.10.5, the response code sent to the logger in webmachine can have
the form `{Code, Msg}`. This patch allows for the incoming code to
have that form or a bare integer and aligns with the default logging
module included in latest wm.
Fix doc string for edoc
Add generated edoc for browsing on github
Make as_io more strict for generic formatting

Previously we attempted to io_lib:format any 2-tuple. This patch adds
a guard that both elements must be lists.

Also using ~p to format floats gives better fideltiy in some cases
without much loss for logging purposes.

And finally: tests!
Merge pull request #6 from opscode/sf/wm-1.10.5-compat

Make opscoderl_wm compatible with webmachine 1.10.5