Formating and syntax fixes that were pointed out during code review.

system/at

@@ -112,7 +112,7 @@ def main():
         if rc != 0:
             module.fail_json(msg=err)
         os.unlink(path)
-        result['changed'] = 'true'
+        result['changed'] = True
     elif script_file:
         result['script_file'] = script_file
         at_command = "%s now + %s %s -f %s" % (ATCMD, unit_count, unit_type, script_file)
@@ -122,7 +122,7 @@ def main():
         rc, out, err = module.run_command(at_command)
         if rc != 0:
             module.fail_json(msg=err)
-        result['changed'] = 'true'
+        result['changed'] = True
     else:
         module.fail_json(msg="command or script_file not specified")