add option to install from system package

[pablodav]

just need a switch:

- include: build-burp.yml 
  when: not burp_install_from_system_package

and a new yml:

- include: install-burp-package.yml
  when: burp_install_from_system_package

maybe also a variable:

burp_system_packages_names:
  - burp-server
  - burp-client

[pablodav]

Just thinking if it makes any sense to keep this open?
Does it provides a real benefit? Current features provides ability to move between almost any bur version and only needs to change the version number in a variable....

[pablodav]

CoffeeITWorks/ansible_burp2_client#3