app/matrix: make cas deployment configurable

This is an alternative to https://gerrit.hackerspace.pl/509 that was
reverted in https://gerrit.hackerspace.pl/541 .

This has already been deployed.

Change-Id: I7d54943c970804cac910e0e15201d1c3fa337489
diff --git a/app/matrix/matrix.hackerspace.pl.jsonnet b/app/matrix/matrix.hackerspace.pl.jsonnet
index e882636..d71dd84 100644
--- a/app/matrix/matrix.hackerspace.pl.jsonnet
+++ b/app/matrix/matrix.hackerspace.pl.jsonnet
@@ -11,6 +11,14 @@
         serverName: "hackerspace.pl",
         cas: {
             enable: true,
+            oauth2: {
+                clientID: "matrix",
+                clientSecret: { secretKeyRef: { name: "oauth2-cas-proxy", key: "oauth2_secret" } },
+                scope: "profile:read",
+                authorizeURL: "https://sso.hackerspace.pl/oauth/authorize",
+                tokenURL: "https://sso.hackerspace.pl/oauth/token",
+                userinfoURL: "https://sso.hackerspace.pl/api/1/profile",
+            },
         },
     },