add release date to whatsnew

finish v0.4.4 whatsnew

update whatsnew for release

update pvsystem and tracking tutorials for pvlib 0.4 api changes (pvl…

…ib#281)

* update pvsystem.ipynb

* update tracking tutorial

* update whatsnew

set date in whatsnew 0.4.1

add release date to whats new

implement simplified solis clear sky model (pvlib#148)

* implement simplified solis. needs tests

* fix index stripping

* add tests. coerce pw to min 0.2

* add simplified solis option to location.get_clearsky. reorder simplified solis output to match ineichen

* update whatsnew

* remove return_raw in favor of OrderedDict. improve nan handling

Merge pull request pvlib#153 from wholmgren/samurlfix

update sam file base url

fix sphinx version lookup problem due to versioneer switch

version=0.3.0, finalize whatsnew release date