Renamed: program instead of method for shell-executer

Change-Id: I4484dc1a5bf0a8158eb3d43ccab4d16ce08d8582

scenarios/misc/static_agent.yaml

@@ -12,7 +12,7 @@ execution:
   -
     title: List all files
     class: shell
-    method: ls -al
+    program: ls -al
   -
     title: Run sample script
     class: shell

shaker/engine/executors/shell.py

@@ -23,8 +23,8 @@ LOG = logging.getLogger(__name__)
 
 class ShellExecutor(base.BaseExecutor):
     def get_command(self):
-        if 'method' in self.test_definition:
-            cmd = base.CommandLine(self.test_definition['method'])
+        if 'program' in self.test_definition:
+            cmd = base.CommandLine(self.test_definition['program'])
         elif 'script' in self.test_definition:
             cmd = base.Script(self.test_definition['script'])
         return cmd.make()