Improved time printing

- Added ability to set precision
- Removed the automatic filling of zeros to the time output
(closes #2763)

The following demonstrate the behavior:

Default:
```
Time Step 16, time = 1.6
                dt = 0.1
```

Fixed width, setting precision (`Outputs/console/time_precision=5`):
```
Time Step 16, time = 1.6000
                dt = 0.10000
```

Scientific ('Outputs/console/scientific_time=true`):
```
Time Step 16, time = 1.600000e+00
                dt = 1.000000e-01
```

Scientific with precision (`Outputs/console/scientific_time=true Outputs/console/time_precision=3`):
```
Time Step 16, time = 1.600e+00
                dt = 1.000e-01
```