CS cleanup of PRG plugin
CS cleanup of PRG plugin

- Created docblock for __invoke() method
- Removed an else condition that would not be hit if the if condition is
  evaluated.

svycka/zend-mvc,ezimuel/zend-mvc,turrsis/zend-mvc,turrsis/zend-mvc,MadCat34/zend-mvc,svycka/zend-mvc,MadCat34/zend-mvc,ezimuel/zend-mvc