Added dig as possible ip resolver

Used shell built-in command -v to determine if dig is installed and if
it is, use it as default for getting the ip-address. Also made the use
of brackets consistent and updated the the way the data variable is
created before it is sent with curl to make it more readable in the
code.

cloudflare-template.sh

@@ -7,7 +7,7 @@ auth_key=""                                        # Your API Token or Global AP
 zone_identifier=""                                 # Can be found in the "Overview" tab of your domain
 record_name=""                                     # Which record you want to be synced
 ttl="3600"                                         # Set the DNS TTL (seconds)
-proxy=false                                        # Set the proxy to true or false
+proxy="false"                                        # Set the proxy to true or false
 slacksitename=""                                   # Title of site "Example Site"
 slackchannel=""                                    # Slack Channel #example
 slackuri=""                                        # URI for Slack WebHook "https://hooks.slack.com/services/xxxxx"
@@ -17,9 +17,15 @@ slackuri=""                                        # URI for Slack WebHook "http
 ###########################################
 ## Check if we have a public IP
 ###########################################
+command -v dig &> /dev/null
+# Use the DNS lookup if dig is available.
+if [[ $? -eq 0 ]]; then 
+    ip=$(dig +short myip.opendns.com @resolver1.opendns.com);
+else
     ip=$(curl -s https://api.ipify.org || curl -s https://ipv4.icanhazip.com/)
+fi
 
-if [ "${ip}" == "" ]; then 
+if [[ "${ip}" == "" ]]; then 
   logger -s "DDNS Updater: No public IP found"
   exit 1
 fi
@@ -27,7 +33,7 @@ fi
 ###########################################
 ## Check and set the proper auth header
 ###########################################
-if [ "${auth_method}" == "global" ]; then
+if [[ "${auth_method}" == "global" ]]; then
   auth_header="X-Auth-Key:"
 else
   auth_header="Authorization: Bearer"
@@ -69,18 +75,28 @@ record_identifier=$(echo "$record" | sed -E 's/.*"id":"(\w+)".*/\1/')
 ###########################################
 ## Change the IP@Cloudflare using the API
 ###########################################
+api_data=$(cat <<EOF
+{
+    "type":"A",
+    "name":"$record_name",
+    "content":"$ip",
+    "ttl":$ttl,
+    "proxied":$proxy
+}
+EOF
+)
 update=$(curl -s -X PATCH "https://api.cloudflare.com/client/v4/zones/$zone_identifier/dns_records/$record_identifier" \
                      -H "X-Auth-Email: $auth_email" \
                      -H "$auth_header $auth_key" \
                      -H "Content-Type: application/json" \
-              --data "{\"type\":\"A\",\"name\":\"$record_name\",\"content\":\"$ip\",\"ttl\":\"$ttl\",\"proxied\":${proxy}}")
+                     --data "$api_data") #"{\"type\":\"A\",\"name\":\"$record_name\",\"content\":\"$ip\",\"ttl\":\"$ttl\",\"proxied\":${proxy}}")
 
 ###########################################
 ## Report the status
 ###########################################
 case "$update" in
 *"\"success\":false"*)
-  logger -s "DDNS Updater: $ip $record_name DDNS failed for $record_identifier ($ip). DUMPING RESULTS:\n$update"
+  echo -e "DDNS Updater: $ip $record_name DDNS failed for $record_identifier ($ip). DUMPING RESULTS:\n$update" | logger -s 
   if [[ $slackuri != "" ]]; then
     curl -L -X POST $slackuri \
     --data-raw '{