Allow for importing without manipulating the rcParams

[mwaskom]

As much as I like the default style (that's why I made it the default), there are situations where people might want to use the plotting functions, but not the style. It actually used to be the case that you would have to call

seaborn.set()

after importing, but I decided that was kind of gross. Once #10 is sorted out it will be easy to revert the style changes that get made, but even then I think it might be nice to have something like

import seaborn.apionly as sns

which would give you the whole namespace, but avoid the call to rcmod.set() in __init__.py.

I'm not sure I've ever seen this design pattern in a Python package so I'm not certain of the correct/clean way to do it. Please pipe up if you have an idea.

[arsenovic]

i would prefer to call set() my self, but since since seaborn is such a high-level package, i may not be the intended audience.

your apionly suggestion sounds reasonable.

[mwaskom]

Closed with #126