Add privileged mode for Docker-in-Docker support

See merge request !5

Certain tools, like code quality, require dind support.

Add IPv6 support

See merge request !4

Support runner options for Docker Machine

See merge request !1

Update README.md

See merge request !3

CI: port Travis config to GitLab

See merge request !2

See #15

Fixed S3 secret key configuration

S3 access key was used as secret key

s3 support added

Add limit option for specific runner

Fix registration check when in Ansible check-mode

When running the playbook in `--check` mode, `gitlab-runner list` still needs to register a result to prevent an error on the following `when` clause.

Fix concurrency auto-detection

Auto-detect runner concurrency based on total CPU threads (vcpus), instead of only processor cores. This accounts for both multiple cores and multiple processors.

See https://stackoverflow.com/questions/39539559/ansible-procesor-count-vs-processor-cores-vs-processor-vcpus

Clean up scripts

package_name: make it possible to latest versions since gitlab 10.0

Docker privileged

debian: add possibility to fix package version number

no clue why i didn't get any email updates from github anymore..