Support timer progress

The fill animation counter gets a number between 0-100.
Example: ```{fill => {fill}}```

It's impossible to make the right timer. The current time can be calculated using the formula: fill * totalTimeInSeconds / 100

However, the timer will not show all seconds if the total time exceeds 100 seconds.
For example, display 10 minutes (600 seconds).
fill 1: 6 seconds
fill 2: 12 seconds
...
fill 100: 600

The timer should work with 1-second step. Making fill bounded to any N makes it possible to use react-native-circular-progress as the timer.