Remove Werror

-Werror shouldn't be used in released code since it can cause random build
failures on moderate warnings. It also depends on the used toolchain since
different toolchains may or may not print the same warnings.

Author: joerg-krause

CMakeLists.txt

@@ -101,7 +101,7 @@ if (CMAKE_CXX_COMPILER_ID MATCHES "Clang")
 elseif ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU")
   # using GCC
   set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Werror -Wall -Wshadow -Wextra -pedantic -Wno-long-long")
-  # not yet ready for -Wconversion
+  # not yet ready for -Wsign-conversion
 endif()
 
 IF(JSONCPP_WITH_WARNING_AS_ERROR)