Update RapidJson name in install script.

Author: viferga

InstallRapidJSON.cmake

@@ -27,15 +27,15 @@ if(NOT RAPIDJSON_FOUND OR USE_BUNDLED_RAPIDJSON)
 		set(RAPIDJSON_URL_MD5 badd12c511e081fec6c89c43a7027bce)
 	endif()
 
-	ExternalProject_Add(RapidJSON
+	ExternalProject_Add(RapidJson
 		DOWNLOAD_NAME	RapidJSON-${RAPIDJSON_VERSION}.tar.gz
 		URL				https://github.com/miloyip/rapidjson/archive/v${RAPIDJSON_VERSION}.tar.gz
 		URL_MD5			${RAPIDJSON_URL_MD5}
 		CMAKE_ARGS		-DCMAKE_INSTALL_PREFIX=<INSTALL_DIR>
 		TEST_COMMAND	""
 	)
 
-	ExternalProject_Get_Property(RapidJSON INSTALL_DIR)
+	ExternalProject_Get_Property(RapidJson INSTALL_DIR)
 
 	set(RAPIDJSON_ROOT_DIR		${INSTALL_DIR})
 	set(RAPIDJSON_INCLUDE_DIRS	${RAPIDJSON_ROOT_DIR}/include)