add options rotate handling
add options rotate handling

for resolv.conf "options rotate" line, enable shuffling of nameservers
before each query. (should just rotate start position and maintain order?).

rcorrieri/dnspython,tow/dnspython,tomlanyon/dnspython,Abhayakara/dnspython,fjxhkj/dnspython,leeclemens/dnspython,cluck/dnspython,preo/dnspython