Parse time for duration expressions

Feature Requests
1

Instead of specifying durations using structured yaml it would be easier to specify them using a human readable string like “30 seconds” or “5 minutes”.

I.e. instead of

for:
  hours: 1
  minutes: 10
  seconds: 5
```
write
```
for: 1 hour, 10 minutes, 5 seconds
```

In practice, I think it is rare that you have to specify more than one unit of time, so instead of
```
for:
  minutes: 1
  seconds: 30
```
you could write
```
for: 1.5 minutes
```
or
```
for: 90 seconds
```

There is a python library that could help:
https://github.com/wroberts/pytimeparse