srsRAN looks for wrong path for config files

[armin485]

Issue Description

Dear srsRAN commity.
First of all I want to thank you for this wonderful project.
I've been installing srsRAN_4G from code with zmq as RF device and it's working great. However, since the applications (EPC, ENB and UE) required to be run with sudo, all of them are trying to read config files in root directory but the build and installation process have been done with my normal user (ubuntu). The typical error I got is:

`ubuntu@zbook:~$ sudo srsepc

Built in Release mode using commit ec29b0c on branch master.

--- Software Radio Systems EPC ---

Couldn't open , trying /root/.config/srsran/epc.conf
Couldn't open /root/.config/srsran/epc.conf either, trying /etc/srsran/epc.conf
Failed to read EPC configuration file /etc/srsran/epc.conf - exiting`

After copying the config files from home directory (ubuntu) into root, it works.

Setup Details

[Specify details of the test setup. This would help us reproduce the problem reliably]
All nework components are running on same machine (my laptop) with zmq as radio transceiver. I've followed official installation and running instruction.

Expected Behavior

sudo srsepc to be run without setting config directories

Actual Behaviour

srsepc, srsenb and srsue all fail to find config files

Steps to reproduce the problem

Installation and building from source including zmp. Follow the official instruction.