Decide if manual attestation duration input should be limited to d,w,m,y

[DMedina6]

SAF CLI is being / was modified to only accept d,w,m,y as inputs for days, weeks, months, years for the duration of the attestation. Before, it was accepting additional inputs such as "fortnightly" or "weekly" in addition to a custom number of units. Decide what the real input should be.