Add a routine to clear nv storage

[ericklein]

Need a routine to clear nv storage in the case of the value pool being incorrect and there is a need for accurate data to be uploaded. If given enough time, the averages will clean themselves of errant values, but if time to report accurate values is critical, we could add a routine to remove all values and let the code restart building the averages.

[ericklein]

nvstorage is now (re)initialized after every sample set is completed.