DOC: Updated whatsnew

Updated whatsnew and added example for vector plots.

List to applicable commits since the last tag release include:

```
$ git log v0.9.0..HEAD --format="%ad %s%n%b" --date=short --no-merges

2013-12-20 pep8 fix

2013-09-23 Improved testing of LambertConformal and Mercator.

2013-12-12 Correct wrapping and clipping of pcolormesh with IGH. Fixes #319.

2013-12-12 Reduced threshold for Stereographic projection.

2013-12-07 Added test for a regional image on a different projection.

2013-12-07 Prevent image interpolation outside original domain. Fixes #358.

2013-12-07 Correct behaviour of origin in imshow. Fixes #359.

2013-12-05 Added streamplot method to GeoAxes.

2013-11-28 Refined projection space regridding.

2013-11-08 Regridding in projection space for vector plots.

2013-10-24 test image permission

2013-09-20 Updated the Hurricane Katrina example to use Lambert Conformal.

2013-09-20 Caught modules which are not importable. This came from applying the summarise package to matplotlib.

2013-09-18 Added barbs method to GeoAxes.

2013-09-17 Allow vectors to be plotted on arbitrary maps. Closes #125.
Adds a transform_vectors method to the CRS class and a quiver
method to the GeoAxes class.
```