work with cookiecutter contexts in yaml

This pr chagne setupCookiecutterVirtualenv function to read context
settings in yaml (default way).

There is no need to convert from json to yaml and back.

Change-Id: Ibc01af020a92720eb985d587b327d6ecbc6c59b1
diff --git a/src/com/mirantis/mk/Python.groovy b/src/com/mirantis/mk/Python.groovy
index 6e4c164..d51362d 100644
--- a/src/com/mirantis/mk/Python.groovy
+++ b/src/com/mirantis/mk/Python.groovy
@@ -229,10 +229,7 @@
 def buildCookiecutterTemplate(template, context, outputDir = '.', path = none) {
     configFile = "default_config.yaml"
     configString = "default_context:\n"
-    for (parameter in context) {
-      configString = "${configString}  ${parameter.key}: \"${parameter.value}\"\n"
-    }
-    writeFile file: configFile, text: configString
+    writeFile file: configFile, text: context
     command = ". ${path}/bin/activate; cookiecutter --config-file ${configFile} --output-dir ${outputDir} --overwrite-if-exists --verbose --no-input ${template}"
     output = sh (returnStdout: true, script: command)
     echo("[Cookiecutter build] Output: ${output}")