Remove raw daily indicators

[rmartz]

Overview

The raw daily indicators have been a bit of a special case for indicators, since they don't need the time aggregation that our indicator framework is built around and aren't used by the lab. That they explicitly do not work with aggregations - a core principle of our indicators - was a cause of concern in #158, and the indicators themselves were made redundant in #162 by virtue that the aggregated variable indicators could be configured to be used for daily "aggregation".

This removes the indicators and increases the flexibility of the basic indicators AverageHighTemperature, AverageLowTemperature, MaxHighTemperature, MaxLowTemperature, and TotalPrecipitation to all permit daily aggregation.

Testing Instructions

• All tests should still pass
• Basic indicators should support daily aggregation and give daily values when requested
  • (Note that daily values have a single data point per day, so average, max and min are indistinguishable)

Closes #172