add function to extract daily tidal data

[galengorski]

I added a function to extract daily signal from the subdaily tidal data. The function is contained within munge_noaa.py and it is called extract_daily_tidal_data. Right now we are extracting 5 different daily metrics:

• water level maximum - minimum
• water level maximum
• water level observed - predicted
• water level filtered using a butterworth filter to extract longer period signals
• mean conductivity

The output files are written as 02_munge/out/noaa_nos_daily_{site}.csv and the subdaily noaa nos data are now written to a subdirectory within the 02_munge/out folder called subdaily

[galengorski]

Going to merge now as @amsnyder is out