Refactor

[a-martynovich]

• for all MTLS requests use a function which makes requests with SSL headers if needed
• improve setup_endpoints (don't modify globals)
• use logging module for logging (Refactor agent to use proper logging #176)
• read dev flag from config.ini (in addition to command line)
• read WOTT_ENDPOINT (and other variables?) from config.ini
• read loglevel from config.ini. Remove "debug" flag, use loglevel with logging
• rewrite some tests which don't test anything, like test_renew_cert
• rewrite run() to be more logically straightforward

[vpetersson]

@a-martynovich when you get a chance - can you update this ticket. It's not urgent, but I think we've already dealt with a few of these.