Add roles for RSK testnet/mainnet

roles/rsk_mainnet.rb

@@ -0,0 +1,11 @@
+name "rsk_mainnet"
+
+run_list %w(
+  kosmos_rsk::rskj
+)
+
+override_attributes(
+  :rskj => {
+    :network => "mainnet"
+  }
+)

roles/rsk_testnet.rb

@@ -0,0 +1,5 @@
+name "rsk_testnet"
+
+run_list %w(
+  kosmos_rsk::rskj
+)