add User#doTasks, convenience method for running multiple tasks at once
fix TestRetrier log messages

when a test succeeds before reaching maxExecutions it must log PASSED, not FAILED
when a test passes after 1 execution, do not write a PASSED log, as it would be a duplicate
redesign PropertyLoader

decouple the details of tinafw's config from PropertyLoader, which is now generic, and not a static class anymore.
add TinaFwPropLoader, focused on tinafw's specific config properties

rename the config file to a more generic "config.(default|custom).properties"
in fact, it is redundant considering the namespace mechanism in the property names