fix(vps-addswap): updates root check

- removed current use of EUID and UID in favour of id

Closes: #482

vps-addswap/install.sh

@@ -7,7 +7,7 @@ __init_vps_addswap() {
     default_size=2G
     my_size=${1:-$default_size}
 
-    if [ "0" != "$EUID" ] && [ "0" != "$UID" ]; then
+    if [ $(id -u) -ne 0 ]; then
         echo Usage:
         echo '        sudo env PATH="$PATH" vps-addswap' $my_size
         exit 1