arrays in matplotlib scatters work now for color, marker, etc.
updated tests for new bubble support
moderately robust 'data' test just looks if value is iterable.

(i.e., if it is, we assume it's data.)

of course, there will be situations where this won't be the case.
users will just need to retain the mpl style in these cases.
Merge pull request #62 from plotly/bubbles

arrays in matplotlib scatters work now for color, marker, etc.