weatherData 0.4
=======================
  
* There is now a distinction being made between `summarized data`
  and `detailed data.` In Summarized Data, one only row per date is returned

* By default, the user will be given `Summarized Data.` You will have to 
  specifically ask for Detailed data, with `opt_detailed=TRUE`

* Depending on the type of weather Data desired (columns), there are now
  three new options: `opt_temperature_columns`, `opt_custom_columns` or 
  `opt_all_columns.` Temperature Columns are the default

* Custom Columns take priority over the other two options. That is, over
  opt_all_columns and `opt_temperature_columns`

* new data set `SFO2013Summarized` has been added. This data is for the
  same period as `SFO2013` but is much more compact

* new `showAvailableColumns` can be used to find out what columns are
  available. Then, the subset of columns desired can be specified using
  `custom_columns.`  Example: `custom_columns = c(1,3,5,6)`

