Revert "Change ".application" to ".app""
Revert "Change ".application" to ".app""

This reverts commit 3c21d75cc9b0de6a402dba0267e963ade6691f15.

artificechicago/camp2016,wcyuan/weather-mailer,dmolson/appengine-guestbook-python,GoogleCloudPlatform/appengine-guestbook-python,bkeyvani/appengine-guestbook-python,jeffgodwyll/appengine-flask-guestbook,bkeyvani/appengine-guestbook-python,jerarl/gcp-appengine-python,thejeshgn/appengine-guestbook-python,artificechicago/camp2016,JackConnor/portfolio,adjohnson916/appengine-guestbook-python,JonGal/appengine-ml-demo,dmolson/appengine-guestbook-python,ashwini0529/appengine-guestbook-python,GoogleCloudPlatform/appengine-guestbook-python,JonGal/appengine-ml-demo,Romzz/appengine-guestbook-python,t9nf/appengine-guestbook-python,ashwini0529/appengine-guestbook-python,wcyuan/weather-mailer,Romzz/appengine-guestbook-python,JackConnor/portfolio,adjohnson916/appengine-guestbook-python,t9nf/appengine-guestbook-python,thejeshgn/appengine-guestbook-python,jerarl/gcp-appengine-python,jeffgodwyll/appengine-flask-guestbook