use namespace for ca and rename CaState to ca::RequestState

Change-Id: I2250bf7fb68503465dae18e16dc3c512fe809037
diff --git a/src/identity-challenge/challenge-email.hpp b/src/identity-challenge/challenge-email.hpp
index 8fc6af5..9dbcedd 100644
--- a/src/identity-challenge/challenge-email.hpp
+++ b/src/identity-challenge/challenge-email.hpp
@@ -57,7 +57,7 @@
 
   // For CA
   std::tuple<ErrorCode, std::string>
-  handleChallengeRequest(const Block& params, CaState& request) override;
+  handleChallengeRequest(const Block& params, ca::RequestState& request) override;
 
   // For Client
   std::vector<std::tuple<std::string, std::string>>
@@ -81,7 +81,7 @@
 
   void
   sendEmail(const std::string& emailAddress, const std::string& secret,
-            const CaState& request) const;
+            const ca::RequestState& request) const;
 
 private:
   std::string m_sendEmailScript;