fix issue if $value can't be exploded

I had the problem that the $value was "-" and the dateSeparator was " - " (with spaces). So the function explode give me a one dimensional array with the $value. From DateRange i get an exception that " - " can't be parsed as date.

This fix compare the $part with the $value and set $parts as array if both are equal.

Also fixes the class name.