[appserver-io/doppelgaenger] Getting ready for PHP 7

[wick-ed]

Doppelgaenger library powers both Design by Contract and AOP functionality within appserver.io. As appserver.io will make a switch to PHP7 in the next version Doppelgaenger has to follow.

UAC:

• PHPUnit tests MUST run within a PHP7 runtime
• Parsing MUST pick up PHP7 specific language constructs
• Expected generator results MUST match pre-PHP7 results