Initial CLI --expiresAfter argument accepts ISO8601, not 10s as documentation indicates

[jbfaden]

The initial CLI interface says that arguments like "60s" or "1d" are accepted, but Duration.parse is used to interpret the argument. I'm using "PT60S" for now, but we should decide if ISO8601 will be used or if a custom parser is better. (I don't have a strong preference.)

[rweigel]

I'd go with ISO given durations in HAPI are ISO. Given we're developing a standard, probably we should also use them when available.

[nobes888]

Replaced the --expire-after option with --stale-after option. This option takes a single parameter (aDura) and can be specified in 3 ways:

[1] A relative duration such that:
         N{d,h,m,s}
     where N represents a number and the unit character {d,h,m,s}
     corresponds to (days, hours, minutes, seconds).
 
 [2] A relative duration expressed as an ISO-8601 string. Example:
         P2DT-3H4M
         PT15M
 
 [3] A duration since an explicit time such as:
         yyyy-MM-dd
         yyyy-MM-ddThh:mm:ss