[#191] runtest.sh: fix bug in deleting actual.txt from previous run (#192)
[#191] runtest.sh: fix bug in deleting actual.txt from previous run (#192)

There are three issues with the logic of 'runtest.sh' for deleting
'./actual.txt' from previous run:

1. It treats 'actual.txt' as a directory (with "-d").
2. It tries to delete 'actual.txt' when it does not exist (with "!").
3. It looks at the wrong directory for 'actual.txt' (with ".."
   instead of ".").

Let's update runtest.sh to fix the above issues.
se-edu/addressbook-level2,se-edu/addressbook-level2