add genuser.sh, fix errors

macOS and Windows might not have htpasswd tools available, so adding this to the tpotinit image. users can run genuser.sh which simply contains a docker command to run tpotinit to create a user and add it to the T-Pot config (.env).
Fix an issue where WEB_USER was added with hyphens
Fix issues where shebang was incorrect
Update .env / env.example

docker/tpotinit/Dockerfile

@@ -10,6 +10,7 @@ RUN apk --no-cache -U add \
         bash \
         bind-tools \
         conntrack-tools \
+		cracklib \
         curl \
         ethtool \
         figlet \