remove JSON parameter list from challenge module and add unified return interfaces for challenge modules

Change-Id: I0e69f7f8ef2ea36f38f11815aa980928b049cdc7
diff --git a/src/ca-config.cpp b/src/ca-config.cpp
index e6ab0f6..c8bc298 100644
--- a/src/ca-config.cpp
+++ b/src/ca-config.cpp
@@ -97,7 +97,7 @@
     if (challengeType == "") {
       BOOST_THROW_EXCEPTION(std::runtime_error("Cannot read type in supported-challenges from the config file"));
     }
-    if (!ChallengeModule::supportChallenge(challengeType)) {
+    if (!ChallengeModule::isChallengeSupported(challengeType)) {
       BOOST_THROW_EXCEPTION(std::runtime_error("Does not support challenge read from the config file"));
     }
     m_supportedChallenges.push_back(challengeType);