start failed due to /var/lib/gitlab-runner not exists
## Summary
start failed due to /var/lib/gitlab-runner not exists
## Steps to reproduce
- ubuntu 17.04
- installed gitlab-ci-multi-runner ( it was a mistake cause outdated )
- then installed correct latest ( https://docs.gitlab.com/runner/install/linux-repository.html )
- registered some runners
- service gitlab-runner start
- if your system lacks of the /var/lib/gitlab-runner directory it fails ( see syslog )
## Actual behavior
- service gitlab-runner status ( not started )
## Expected behavior
- it should ensure /var/lib/gitlab-runner ( may a package post-install check could enough )
## Relevant logs and/or screenshots
/var/log/syslog :
```
Dec 24 03:47:25 srv2 systemd[1]: Started GitLab Runner.
Dec 24 03:47:25 srv2 gitlab-runner[602]: time="2017-12-24T03:47:25+01:00" level=info msg="Starting multi-runner from /etc/gitlab-runner/config.toml ..." builds=0
Dec 24 03:47:25 srv2 gitlab-runner[602]: time="2017-12-24T03:47:25+01:00" level=info msg="Running in system-mode."
Dec 24 03:47:25 srv2 gitlab-runner[602]: time="2017-12-24T03:47:25+01:00" level=info msg="Starting multi-runner from /etc/gitlab-runner/config.toml ..." builds=0
Dec 24 03:47:25 srv2 gitlab-runner[602]: time="2017-12-24T03:47:25+01:00" level=info msg="Running in system-mode."
Dec 24 03:47:25 srv2 gitlab-runner[602]: time="2017-12-24T03:47:25+01:00" level=info
Dec 24 03:47:25 srv2 gitlab-runner[602]: time="2017-12-24T03:47:25+01:00" level=fatal msg="chdir /var/lib/gitlab-runner: no such file or directory"
Dec 24 03:47:25 srv2 gitlab-runner[602]: time="2017-12-24T03:47:25+01:00" level=info
Dec 24 03:47:25 srv2 gitlab-runner[602]: time="2017-12-24T03:47:25+01:00" level=fatal msg="chdir /var/lib/gitlab-runner: no such file or directory"
Dec 24 03:47:25 srv2 systemd[1]: gitlab-runner.service: Main process exited, code=exited, status=1/FAILURE
Dec 24 03:47:25 srv2 systemd[1]: gitlab-runner.service: Unit entered failed state.
Dec 24 03:47:25 srv2 systemd[1]: gitlab-runner.service: Failed with result 'exit-code'.
```
## Environment description
```
root@phy:/etc/gitlab-runner# docker info
Containers: 16
Running: 13
Paused: 0
Stopped: 3
Images: 233
Server Version: 17.09.1-ce
Storage Driver: overlay2
Backing Filesystem: extfs
Supports d_type: true
Native Overlay Diff: true
Logging Driver: json-file
Cgroup Driver: cgroupfs
Plugins:
Volume: local
Network: bridge host macvlan null overlay
Log: awslogs fluentd gcplogs gelf journald json-file logentries splunk syslog
Swarm: inactive
Runtimes: runc
Default Runtime: runc
Init Binary: docker-init
containerd version: 06b9cb35161009dcb7123345749fef02f7cea8e0
runc version: 3f2f8b84a77f73d38244dd690525642a72156c64
init version: 949e6fa
Security Options:
apparmor
seccomp
Profile: default
Kernel Version: 4.10.0-19-generic
Operating System: Ubuntu 17.04
OSType: linux
Architecture: x86_64
CPUs: 8
Total Memory: 31.16GiB
Name: phy
ID: QSK5:5N6W:NPZ6:EM7F:GBTE:VFO5:QM6U:OTSS:WB3T:BIYD:QGB2:5XSU
Docker Root Dir: /var/lib/docker
Debug Mode (client): false
Debug Mode (server): false
Registry: https://index.docker.io/v1/
Experimental: false
Insecure Registries:
127.0.0.0/8
Live Restore Enabled: false
WARNING: bridge-nf-call-iptables is disabled
WARNING: bridge-nf-call-ip6tables is disabled
```
### Used GitLab Runner version
```
root@phy:/etc/gitlab-runner# gitlab-runner -v
Version: 10.3.0
Git revision: 5cf5e19a
Git branch: 10-3-stable
GO version: go1.8.5
Built: Fri, 22 Dec 2017 08:47:19 +0000
OS/Arch: linux/amd64
```
issue