Add session data to env vars

Currently the session secret can only be set by config.json or docker
secrets. This creates a problem on Heroku hosted instances that can not
set a session secret.

Since we automatically generate them on startup this results in an
logout of all users on every config change in Heroku.

Signed-off-by: Sheogorath <sheogorath@shivering-isles.com>

lib/config/environment.js

@@ -26,6 +26,8 @@ module.exports = {
   allowFreeURL: toBooleanConfig(process.env.HMD_ALLOW_FREEURL),
   defaultPermission: process.env.HMD_DEFAULT_PERMISSION,
   dbURL: process.env.HMD_DB_URL,
+  sessionSecret: process.env.HMD_SESSION_SECRET,
+  sessionLife: toIntegerConfig(process.env.HMD_SESSION_LIFE),
   imageUploadType: process.env.HMD_IMAGE_UPLOAD_TYPE,
   imgur: {
     clientID: process.env.HMD_IMGUR_CLIENTID