Cannot disable Phone Home from read-only filesystem

[tcostigl]

If dlr is installed in a directory not writable by the user, attempting to disable the PhoneHome feature will fail.

Reproduce:

• With dlr-1.10.0 installed in a non-user writable directory run python
• from dlr.counter.phone_home import PhoneHome
• PhoneHome.disable_feature()
• PermissionError: [Errno 13] Permission denied:...

Expected behavior:

• The PhoneHome feature is disabled for this session