`kwargs` are ignored in `Series.plot`
It seems that some `kwargs` (like `mew` and `ms`) given to the `Series.plot` method are being ignored.

I'm running pandas.0.8.0 and matplotlib 1.1.0 on Archlinux, Python 2.7.3 with ipython 0.12.1, and starting ipython via `ipython2 --pylab=qt`.

The following code produces the erroneous behaviour. The mpl plotting works just fine, whereas the pandas plotting ignores `ms` and `mew` arguments.

```
import matplotlib as mpl
from numpy import random
import pandas
print pandas.__version__

test = pandas.Series(random.randn(120),
                     index=pandas.date_range(start="2000-01-01",
                                             end="2009-12-31",
                                             freq=pandas.datetools.MonthBegin()))

mpl.pyplot.figure()
# this produces the correct markers
mpl.pyplot.plot(test, '.', ms=12.)

mpl.pyplot.figure()
# this ignores the ms kwarg
test.plot(style='.', ms=12.)
```

It would be okay to use matplotlib's plotting function, but I'm dealing with time series, and I don't think matplotlib's support for dates is too convenient.

Is this a bug, or am I just doing it wrong?
