Andrei Sedoi

Add option to preserve file permissions when collecting files for RPM from a POSIX file system

2

It's quite annoying to explicitly specify file permissions when building an RPM, especially when files are collected from multiple sources maintained by different teams or there are many executable files...

Replicating the issue: ```bash $ rebar3 new release foo ===> Writing foo/apps/foo/src/foo_app.erl ===> Writing foo/apps/foo/src/foo_sup.erl ===> Writing foo/apps/foo/src/foo.app.src ===> Writing foo/rebar.config ===> Writing foo/config/sys.config ===> Writing foo/config/vm.args ===> Writing foo/.gitignore...