Account::_accountID: constify

It is set by the constructor
No need to unserialize it again either

sflphone-common/src/account.h

@@ -364,7 +364,7 @@ class Account : public Serializable
         /**
          * Account ID are assign in constructor and shall not changed
          */
-        std::string _accountID;
+        const std::string _accountID;
 
         /**
          * Account login information: username

sflphone-common/src/iax/iaxaccount.cpp

@@ -97,7 +97,6 @@ void IAXAccount::unserialize (Conf::MappingNode *map)
 
     map->getValue(aliasKey, &_alias);
     map->getValue(typeKey,  &_type);
-    map->getValue(idKey,    &_accountID);
     map->getValue(usernameKey, &_username);
     map->getValue(passwordKey, &_password);
     map->getValue(hostnameKey, &_hostname);

sflphone-common/src/sip/sipaccount.cpp

@@ -296,7 +296,6 @@ void SIPAccount::unserialize (Conf::MappingNode *map)
 
     map->getValue(aliasKey, &_alias);
     map->getValue(typeKey, &_type);
-    map->getValue(idKey, &_accountID);
     map->getValue(usernameKey, &_username);
     map->getValue(authenticationUsernameKey, &_authenticationUsername);
     map->getValue(passwordKey, &_password);