Fix for EtherCalc IE image specification.

Will allow EtherCalc to work in 17.05.

config/plugins/interactive_environments/ethercalc/config/allowed_images.yml.sample

@@ -0,0 +1,11 @@
+# This file lists acceptable images to allow runing.
+#
+# This allows you, the admin, to create multiple flavours
+# for your users to run. E.g. maybe you need a geosciences flavour,
+# you can create the image based on our default image and add the
+# appropriate `apt-get/pip install` statements.
+---
+-
+    image: shiltemann/ethercalc-galaxy-ie:17.05
+    description: |
+        EtherCalc is a web spreadsheet.

config/plugins/interactive_environments/ethercalc/config/ethercalc.ini.sample

@@ -12,9 +12,6 @@
 # usual group/sudo changes.
 #command = docker {docker_args}
 
-# The docker image name that should be started.
-image = shiltemann/ethercalc-galaxy-ie:17.05
-
 # Additional arguments that are passed to the `docker run` command.
 #command_inject = --sig-proxy=true -e DEBUG=false