Move plot into MPLFitter; support style args; improve docstrings.
Cleanups import and unused variables, fix typo.
Merge pull request #2 from tritemio/fitter-plotting

Cleanups import and unused variables, fix typo (min -> max).
Merge pull request #124 from danielballan/fitter-plotting

Move plot into MPLFitter; support style args; improve docstrings.