Fix Valgrind reporting memory leaks

Created by: stac47

Hello,

Let us consider the following program:

#include <string>
#include <handystats/core.hpp>

namespace {

const std::string kJsonConfig =
"{\
    \"metrics\": {\
        \"timer\": {\
            \"idle-timeout\": 500000,\
            \"tags\": [\"min\",\"max\",\"avg\",\"count\",\"moving-avg\",\"moving-count\"]\
        },\
        \"gauge\": {\
            \"tags\": [\"min\",\"max\",\"avg\",\"moving-avg\"]\
        },\
        \"counter\": {\
        }\
    },\
    \"metrics-dump\": {\
        \"interval\": 10000\
    },\
    \"json-dump\": {\
        \"interval\": 10000\
    }, \
    \"statistics\": {\
        \"moving-interval\": 3600000,\
        \"histogram-bins\": 720\
    }\
}";

} /* namespace  */

int main(int argc, const char *argv[])
{
    HANDY_CONFIG_JSON(kJsonConfig.c_str());
    HANDY_INIT();
    HANDY_FINALIZE();
    return 0;
}

Running Valgrind on this leads definitive memory lost.

==3008== Memcheck, a memory error detector ==3008== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al. ==3008== Using Valgrind-3.13.0 and LibVEX; rerun with -h for copyright info ==3008== Command: ./a.out ==3008== ==3008== ==3008== HEAP SUMMARY: ==3008== in use at exit: 65,713 bytes in 5 blocks ==3008== total heap usage: 50 allocs, 45 frees, 358,863 bytes allocated ==3008== ==3008== 65,713 (24 direct, 65,689 indirect) bytes in 1 blocks are definitely lost in loss record 5 of 5 ==3008== at 0x4C2C25F: operator new(unsigned long) (vg_replace_malloc.c:334) ==3008== by 0x4E4C0C4: __shared_count<rapidjson::GenericDocument<rapidjson::UTF8<> >> (shared_ptr_base.h:584) ==3008== by 0x4E4C0C4: __shared_count<rapidjson::GenericDocument<rapidjson::UTF8<> >> (shared_ptr_base.h:595) ==3008== by 0x4E4C0C4: __shared_ptr<rapidjson::GenericDocument<rapidjson::UTF8<> > > (shared_ptr_base.h:1079) ==3008== by 0x4E4C0C4: reset<rapidjson::GenericDocument<rapidjson::UTF8<> > > (shared_ptr_base.h:1243) ==3008== by 0x4E4C0C4: handystats::config::reset() (config.cpp:172) ==3008== by 0x400F899: call_init.part.0 (dl-init.c:72) ==3008== by 0x400F9AA: call_init (dl-init.c:30) ==3008== by 0x400F9AA: _dl_init (dl-init.c:120) ==3008== by 0x4000C59: ??? (in /lib/x86_64-linux-gnu/ld-2.24.so) ==3008== ==3008== LEAK SUMMARY: ==3008== definitely lost: 24 bytes in 1 blocks ==3008== indirectly lost: 65,689 bytes in 4 blocks ==3008== possibly lost: 0 bytes in 0 blocks ==3008== still reachable: 0 bytes in 0 blocks ==3008== suppressed: 0 bytes in 0 blocks ==3008== ==3008== For counts of detected and suppressed errors, rerun with: -v ==3008== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)

Tell me if this needs to be reworked. Stac