Writing data in "readMifare" example not correctly implemented

In the "readMifare"-example you can uncomment the lines 107 and 108 to write "adafruit.com" to sector 4 as a test. Uncommenting the lines causes the following compiler error

    readMifare.pde: In function 'void loop()':
    readMifare:107: error: expected primary-expression before '{' token
    readMifare:107: error: expected `;' before '{' token

with the reason being that you cannot assign an array after declaration.
To fix that, you can use `memcpy` to fill the data-array:

```c
memcpy(data, (const uint8_t[]){ 'a', 'd', 'a', 'f', 'r', 'u', 'i', 't', '.', 'c', 'o', 'm', 0, 0, 0, 0 }, sizeof data);
```

Furthermore, I have cleaned up the indentation to be two spaces all the way through, some comments were indented using tabs.