Renaming files to be PSR-0 compatible
Fixing PHPdoc
After "$field->column" there was something that looked like a space but was not. Now it is a normal space.
Only Sprig_Field_Password has hash_with

This helps my IntelliJ IDE to understand $field->hash_with (was telling
me that Sprig_Field does not have a hash_with field)
$this->_model is not lower case after the last changes in my Sprig version
_unique_field is compatible with the new Validation framework from Kohana