Allow set a instance folder

[yodatak]

For now the folder instance is created from the instance name , it could be interesting to have a specifiy variable for instance folder different from instance name.

Are you open for a PR ?

[robertdebock]

Absolutely open for a PR, go ahead. Don't worry too much if it's good or not, lets start and see what's usable.

[yodatak]

The PR i created maybe it could be interesting to change the default and to rename the variables
#53

tomcat_directory: /opt
tomcat_folder: tomcat_8

to
tomcat_install_folder: /opt
tomcat_default_instance_folder: tomcat_8

and mabye latter refactor the varaibles

I test on molecule test in podman and it work for me