108 update package cache

Closes #108 and #94

See merge request openappstack/bootstrap!64

Use branch name for image builds

See merge request openappstack/bootstrap!63

Unfortunatly, we still need to update two times the apt package cache:

1. In the very first task before we can install any package (#108).
   apt-transport-https needs to get installed before we can configure
   the docker apt repo (2.)
2. After configuring the docker apt repo, and before installing the
   docker-ce package.

Closes #108

Add cosmos functions

See merge request openappstack/bootstrap!56

Right now every branch will push to the same image tag,
which brakes deployments from time to time (see
https://code.greenhost.net/openappstack/bootstrap/-/jobs/22571 i.e.).

Ignore all custom settings and inventory files

See merge request openappstack/bootstrap!61

I had multiple custom files for 2 clusters I maintain,
so I wanted to gitignore them all.

Resolve "bootstrap fails if release_name has upper case characters"

Closes #44

See merge request openappstack/bootstrap!52

Resolve "Replace traefik by nginx and cert-manager"

Closes #116

See merge request openappstack/bootstrap!55

Use debian instead of ubuntu

See merge request openappstack/bootstrap!53

This is a prerequisite to properly removing domain records (#114).

- delete_domain_record()
- delete_domain_records_by_name()
- get_domain_records_by_name()

Resolve "Remove keycloak from CI pipeline"

Closes #117

See merge request openappstack/bootstrap!57

Deploy OAS apps to dedicated namespaces

See merge request openappstack/bootstrap!46

Allow production le certs

Closes #91

See merge request openappstack/bootstrap!49

Point to online docs from README.md

Closes #18

See merge request openappstack/bootstrap!44