Set delay to an int to prevent TypeError

On Python3.3 on Kali I was getting a TypeError when using the -d (delay) switch. Looks like it was being read as a string, and then treated as an int later on in the script.

```
# python3.3 incept unlock -d 30
<...>
[!] Warning: Something went dreadfully wrong, full stack trace below: unsupported operand type(s) for -: 'str' and 'int'

Traceback (most recent call last):
  File "incept", line 164, in main
    device, memsize = interface.initialize(opts, module)
  File "/root/inception/inception/interfaces/firewire.py", line 75, in initialize
    device = fw.getdevice(device_index, elapsed)
  File "/root/inception/inception/interfaces/firewire.py", line 260, in getdevice
    'or press Ctrl+C', seconds=self.delay - elapsed)
TypeError: unsupported operand type(s) for -: 'str' and 'int'
```