Issue #715. Wrong URI construction in Yii1 module

This fixes the issue and adds some flexibility to this part of the code.
This code will understand URI's like:
```
$I->amOnPage('site/signup');
$I->amOnPage('/site/signup');
$I->amOnPage('index-test.php/site/signup');
$I->amOnPage('/index-test.php/site/signup');
$I->amOnPage('/index-test.php/site/signup?blah=blah');
$I->amOnPage('?blah=blah');
```

And so on.