support 'pre' execution for actions. (#389)

src/Test/TestData/nodeaction_init_default.yml

@@ -0,0 +1,21 @@
+name: 'Hello World'
+description: 'Greet the world and record the time'
+author: 'Test Corporation'
+inputs: 
+  greeting: # id of input
+    description: 'The greeting we choose - will print ""{greeting}, World!"" on stdout'
+    required: true
+    default: 'Hello'
+    deprecationMessage: 'This property has been deprecated'
+  entryPoint: # id of input
+    description: 'optional docker entrypoint overwrite.'
+    required: false
+outputs:
+  time: # id of output
+    description: 'The time we did the greeting'
+icon: 'hello.svg' # vector art to display in the GitHub Marketplace
+color: 'green' # optional, decorates the entry in the GitHub Marketplace
+runs:
+  using: 'node12'
+  main: 'main.js'
+  pre: 'init.js'