settings cant have an equals sign

by splitting on = and only checking on the exact count, passwords and
possible other settings that can contain a = are dropped rendering
muttvcardsearch unusable.

fixed by checking if there are more than 2 parts in the split and assume
the first = is between key and value, the rest is combined again into
the value

Signed-off-by: BlackEagle <ike.devolder@gmail.com>