ENH: add_field and add_field_like methods on Radar object
ENH: info method added to Radar object
MAINT: renamed netcdf to cfradial in functions/classes
ENH: RadarDisplay.plot_ray method.

* plot_ray method added to RadarDisplay class for plotting individual rays.
* RadarDisplay unit tests updated for more complete coverage.
* LP Phase Proc example updated to use new plot_ray method.
* Removed rayplot.py file as functionality now present in RadarDisplay.
MAINT: Removed unused sounding module
BUG: read_sigmet now works with Python 2.6
Merge pull request #87 from jjhelmus/master

Various small enhancements, maintanance, and bug fixed