Updated edxapp to use JWT variables from common_vars

This will help ensure that all services built for devstack stay synchronized.

LEARNER-817

playbooks/roles/edxapp/defaults/main.yml

@@ -319,10 +319,10 @@ EDXAPP_BULK_EMAIL_LOG_SENT_EMAILS: false
 EDXAPP_UNIVERSITY_EMAIL: 'university@example.com'
 EDXAPP_PRESS_EMAIL: 'press@example.com'
 EDXAPP_LMS_ROOT_URL: "{{ EDXAPP_LMS_BASE_SCHEME | default('https') }}://{{ EDXAPP_LMS_BASE }}"
-EDXAPP_LMS_ISSUER: "{{ EDXAPP_LMS_ROOT_URL }}/oauth2"
+EDXAPP_LMS_ISSUER: "{{ COMMON_JWT_ISSUER }}"
 EDXAPP_JWT_EXPIRATION: 30  # Number of seconds until expiration
-EDXAPP_JWT_AUDIENCE: "lms-key"
-EDXAPP_JWT_SECRET_KEY: "lms-secret"
+EDXAPP_JWT_AUDIENCE: "{{ COMMON_JWT_AUDIENCE }}"
+EDXAPP_JWT_SECRET_KEY: "{{ COMMON_JWT_SECRET_KEY }}"
 
 EDXAPP_PLATFORM_TWITTER_ACCOUNT: '@YourPlatformTwitterAccount'
 EDXAPP_PLATFORM_FACEBOOK_ACCOUNT: 'http://www.facebook.com/YourPlatformFacebookAccount'