Failing test with current Integer Generator

```
1) Eris\Generator\IntegerTest::testShouldEventuallyGenerateAllTheValues
Only generated the following values: array (
        0 => 5,
        1 => 4,
        2 => 3,
        3 => 6,
        )
Failed asserting that 4 matches expected 5.
```
I am missing something...
```
[20:50:55][giorgio@Bipbip:~/code/eris]$ php -r 'for ($i = 0; $i < 20; $i++) { var_du
mp(rand(-1000, 1000)); }'
int(221)
int(663)
int(604)
int(710)
int(12)
int(-424)
int(642)
int(-755)
int(77)
int(159)
int(-368)
int(852)
int(201)
int(792)
int(7)
int(402)
int(40)
int(357)
int(26)
int(-726)
```
So why were we doing the positive interval stuff?