Add cipher cfg param for modem and bts

This parameter is contains a list of supported encryption ciphers by the
modem or bts setting it. It is so far not directly/automatically used
inside osmo-gsm-tester code, but can be useful to create scenarios for
tests that require specific ciphering modes.
For instance, aoip_encryption suite contains tests that require a BTS and
a modem that supports a5 0 and a5 1, otherwise tests will fail.

Change-Id: Ic0e368843a6e58bd3eeef36d2c0a7501296f0f3e
diff --git a/example/scenarios/cipher-a50.conf b/example/scenarios/cipher-a50.conf
new file mode 100644
index 0000000..107172b
--- /dev/null
+++ b/example/scenarios/cipher-a50.conf
@@ -0,0 +1,7 @@
+resources:
+  bts:
+  - ciphers:
+    - a5_0
+  modem:
+  - ciphers:
+    - a5_0