Resolve symlinks in config directory
Resolve symlinks in config directory

Docker/Openshift/Kubernetes mount the config file as a symbolic link and
IsDir returns true if the file is a symlink. Before calling IsDir, the
symlink should be resolved to determine if it points at a file or
directory.

Fixes #3753

vamage/consul,kingland/consul,kingland/consul,youhong316/consul,scalp42/consul,youhong316/consul,42wim/consul,42wim/consul,hashicorp/consul,calgaryscientific/consul,i0rek/consul,i0rek/consul,42wim/consul,scalp42/consul,youhong316/consul,hashicorp/consul,i0rek/consul,hashicorp/consul,calgaryscientific/consul,calgaryscientific/consul,hashicorp/consul,vamage/consul,calgaryscientific/consul,youhong316/consul,vamage/consul,scalp42/consul,scalp42/consul,kingland/consul,vamage/consul,kingland/consul,calgaryscientific/consul,youhong316/consul,i0rek/consul,vamage/consul,i0rek/consul,42wim/consul,kingland/consul,scalp42/consul,42wim/consul