Do not assume sudo is present

- On Digital Ocean and perhaps other platforms, the user is root by default
  and sudo is uninstalled

letsencrypt-auto

@@ -10,6 +10,12 @@ VENV_NAME="letsencrypt"
 VENV_PATH=${VENV_PATH:-"$XDG_DATA_HOME/$VENV_NAME"}
 VENV_BIN=${VENV_PATH}/bin
 
+if test "`id -u`" -ne "0" ; then
+  SUDO=sudo
+else
+  SUDO=
+fi
+
 for arg in "$@" ; do 
   # This first clause is redundant with the third, but hedging on portability
   if [ "$arg" = "-v" ] || [ "$arg" = "--verbose" ] || echo "$arg" | grep -E -- -v+ ; then
@@ -28,16 +34,16 @@ then
   fi
   if [ -f /etc/debian_version ] ; then
     echo "Bootstrapping dependencies for Debian-based OSes..."
-    sudo $BOOTSTRAP/_deb_common.sh
+    $SUDO $BOOTSTRAP/_deb_common.sh
   elif [ -f /etc/arch-release ] ; then
     echo "Bootstrapping dependencies for Archlinux..."
-    sudo $BOOTSTRAP/archlinux.sh
+    $SUDO $BOOTSTRAP/archlinux.sh
   elif [ -f /etc/redhat-release ] ; then
     echo "Bootstrapping dependencies for RedHat-based OSes..."
-    sudo $BOOTSTRAP/_rpm_common.sh
+    $SUDO $BOOTSTRAP/_rpm_common.sh
   elif uname | grep -iq FreeBSD ; then
     echo "Bootstrapping dependencies for FreeBSD..."
-    sudo $BOOTSTRAP/freebsd.sh
+    $SUDO $BOOTSTRAP/freebsd.sh
   elif uname | grep -iq Darwin ; then
     echo "Bootstrapping dependencies for Mac OS X..."
     echo "WARNING: Mac support is very experimental at present..."
@@ -71,5 +77,5 @@ fi
 
 # Explain what's about to happen, for the benefit of those getting sudo
 # password prompts...
-echo "Running with virtualenv:" sudo $VENV_BIN/letsencrypt "$@"
-sudo $VENV_BIN/letsencrypt $@
+echo "Running with virtualenv:" $SUDO $VENV_BIN/letsencrypt "$@"
+$SUDO $VENV_BIN/letsencrypt $@