Incorrect behavior if one of checks failed

[Nastradamus]

Exit code catched incorrectly:

[vyagofarov@mac:~/git/healthcheck] $ ./check -h localhost -p 5432 --username vyagofarov --dbname postgres --project dummy
[2018-11-21T11:37:04+0300] ========== Perform check: ==========
[2018-11-21T11:37:04+0300] ./resources/checks/A001_system_info.sh
[2018-11-21T11:37:04+0300]
./resources/checks/A001_system_info.sh: line 13: lscpu: command not found
cat: /proc/meminfo: No such file or directory
df: option requires an argument -- T
usage: df [-b | -H | -h | -k | -m | -g | -P] [-ailn] [-T type] [-t] [filesystem ...]
./resources/checks/A001_system_info.sh: line 53: hostnamectl: command not found
[2018-11-21T11:37:04+0300] ========== End of check ===========
[2018-11-21T11:37:04+0300] check 'A001_system' is finished
[2018-11-21T11:37:04+0300] Artifacts saved at: './artifacts/dummy/2018_11_21T11_37_04_+0300/A001_system.json'

Should be:

WARNING: check '${check_id}' failed with error ^^^

[Nastradamus]

Fixed in attached branched and merged to master.