DCOM-229: DocParser - add support for php5 MyClass::class call to get path of the class

[doctrinebot]

Jira issue originally created by user umed:

When I try to use in my annotations

Career::class

I get Semantical Error. Career is imported, so I dont want to use full class path name again. How about to add this feature to support by annotations?
We need to add some code like this (DocParser#Constant):

            if ($found) {
                 if ($const === 'class') {
                    return $className;
                 }

                 $identifier = $className . '::' . $const;
            }
        }

        if (!defined($identifier)) {
            throw AnnotationException::semanticalErrorConstants($identifier, $this->context);
        }

        return constant($identifier);

[guilhermeblanco]

This issue was moved to doctrine/annotations#84