Description of problem:
When running dnf module list as non-root you get a permissions error.

Version-Release number of selected component (if applicable):
dnf-0:2.7.5-8

Steps to Reproduce:
[user@localhost ~]$ dnf module list
Fedora Modular 28 - x86_64 511 kB/s | 244 kB 00:00
Fedora Modular 28 - x86_64 - Updates 875 B/s | 257 B 00:00
Fedora Modular 28 - x86_64 - Test Updates 169 kB/s | 129 kB 00:00
Fedora 28 - x86_64 - Test Updates 12 MB/s | 11 MB 00:00
Fedora 28 - x86_64 - Updates 771 B/s | 257 B 00:00
^[[OFedora 28 - x86_64 51% [====================================== ] 6.3 MB/s | 31 MB 00:04 ^[[I^[[OFedora 28 - x86_64 71% [=====================================================- ] 8.4 MB/s | 43 MB 00Fedora 28 - x86_64 33 MB/s | 60 MB 00:01
Last metadata expiration check: 0:00:00 ago on Tue 27 Mar 2018 04:12:48 PM EDT.
[Errno 13] Permission denied: '/etc/dnf/modules.d'