domains file is not read with python3

[fanto666]

when sending SIGUSR1 to living prints:
vrfydmn-0.11.0 milter Postfix domains: [/, e, t, c, /, v, r, f, y, d, m, n, ., d, o, m, a, i, n, s...]

looks like instead of reading the file into memory its name is split as the domain list.

[fanto666]

this seems to be problem of python3 changes, because nearly the same code in 0.9.1 works properly with python2
unfortunately my python knowledge is nearly none

[fanto666]

I can confirm that pull-request #11 fixes the problem.