Updates as discussed with Evgeni

Removed install: target from Makefile
Removed commented-out netaddr code
Using 'for line in whitelist_fh:' instead of 'while 1:'
bley.conf.example now uses relative paths for whitelist_*_file
created static variable regexp_type
changed variable name allowdomain -> entry_wl
changed domains and addresses in test/test_bley.py to use rfc2606/rfc3849/rfc5735
removed bley.conf from setup.py, whitelist_clients.example
Additional:
Added static whitelist for 'postmaster@' when whitelist file is not found