Some patches

[dpesce]

There are a couple of bugs that were introduced in the last version update that remain outstanding. This patch fixes the known ones. Specifically, this update:

• Closes Bug with new flag when weight>0 #26 so that a weight parameter >0 can be used with the flagday=True setting.
• Closes Missing eat dependency #28 so that users can actually run ngehtsim without needing to install eat.

Additionally, there are some other updates packaged along with this patch:

• A couple new sites have been added to the database: HESS and ZUG
• The weather database has been updated to include weather info dating back through the year 1980
• Some initial polarization basis awareness code has been added; it is turned off by default as it remains a work in progress