Feat: dependency handling and fail tasks

[dschier-wtd]

As a developer, I don't want to handle dependencies, but fail my role, if the requirements are not met.

Criteria

• use fact modules + debug + fail for failing instead of pulling dependencies

• requirements.yml should be maintained anyway

• [x] updated ansible-skeleton (docs/guidelines and examples in meta/main.yml)

• [x] check roles for meta/main.yml dependencies

• [ ] remove roles dependencies

• [ ] update roles to fail, if req not met

[dschier-wtd]

identified only 2 roles which need some attention:

app_ansible app_bash

[dschier-wtd]

all roles done.