Log Message:
Update pandas to 0.12.0.

This is a major release from 0.11.0 and includes several new features
and enhancements along with a large number of bug fixes.

Highlites include a consistent I/O API naming scheme, routines to read
html, write multi-indexes to csv files, read & write STATA data files,
read & write JSON format files, Python 3 support for HDFStore, filtering
of groupby expressions via filter, and a revamped replace routine that
accepts regular expressions.

For detailed changes see:
http://pandas.pydata.org/pandas-docs/stable/whatsnew.html