New way to deal with incomplete dt columns. Leaving the NA's as they come, and adding a date column.

Fixes #140. So now, if a column that is modernly displaying date and time, it still gets returned as a POSIXct dateTime. If some of those columns are only dates, a time of noon...with the median time zone offset...is added, and a new column is created to indicate a TRUE/FALSE date flag.

Hard coding dates for unit value data. Otherwise, might ask for data from the future if outside the appropriate timezone.

Added some easy checks to the water quality data to assure that the number of samples returned matched what the water quality portal said should return.