TimeSeriesAxes.set_scale doesn't allow kwargs, breaks loglog

The TimeSeriesAxes object over-writes the set_xscale method, and doesn't allow for kwargs, so loglog breaks:

>>> from gwpy.plotter import TimeSeriesPlot
>>> fig = TimeSeriesPlot()
>>> ax = fig.gca()
>>> ax.loglog([1, 2, 3, 4, 5])
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/duncan.macleod/opt/gwpysoft/lib/python2.6/site-packages/matplotlib/axes/_axes.py", line 1557, in loglog
    self.set_xscale('log', **dx)
TypeError: set_xscale() got an unexpected keyword argument 'basex'