Provide methods to supply options for curl, fetch, and wget

I wanted this to specify -4 on fetch calls. My host had an IPv6
address but no public IPv6 network access.  Supplying this option
specifies that only IP4 should be used on fetch.

README.md

@@ -67,7 +67,9 @@ USER_AGENT="--user-agent='anvil-cert-puller'"
 FETCH="/usr/bin/fetch --mirror --quiet --user-agent=${USER_AGENT}'"
 CURL="/usr/local/bin/curl --silent --user-agent '${USER_AGENT}' --remote-time"
 WGET="/usr/local/bin/wget --quiet --user-agent='${USER_AGENT}'"
-
+FETCH_OPTIONS="-4"
+CURL_OPTIONS="-4"
+WGET_OPTIONS="-4"
 ```
 
 After getting new certs, services need to be restarted/reloaded.

cert-puller

@@ -125,15 +125,15 @@ fetch_new_certs(){
       case ${FETCH_TOOL} in
         "wget")
           ${LOGGER} running: ${WGET} --output-document=${DOWNLOAD_DIR}/${file} ${CERT_SERVER}/${cert}/${file}
-          ${WGET} --output-document=${DOWNLOAD_DIR}/${file} ${CERT_SERVER}/${cert}/${file}
+          ${WGET} ${WGET_OPTIONS} --output-document=${DOWNLOAD_DIR}/${file} ${CERT_SERVER}/${cert}/${file}
           ;;
         "curl")
           ${LOGGER} running: ${CURL} -o ${DOWNLOAD_DIR}/${file} ${CERT_SERVER}/${cert}/${file}
-          ${CURL} -o ${DOWNLOAD_DIR}/${file} ${CERT_SERVER}/${cert}/${file}
+          ${CURL} ${CURL_OPTIONS} -o ${DOWNLOAD_DIR}/${file} ${CERT_SERVER}/${cert}/${file}
           ;;
         *)
           ${LOGGER} running: ${FETCH} -o ${DOWNLOAD_DIR} ${CERT_SERVER}/${cert}/${file}
-          ${FETCH} -o ${DOWNLOAD_DIR} ${CERT_SERVER}/${cert}/${file}
+          ${FETCH} ${FETCH_OPTIONS} -o ${DOWNLOAD_DIR} ${CERT_SERVER}/${cert}/${file}
           ;;
       esac
       RESULT=$?