Evaluate ${PATH} when outputted code is eval'd.

It was previously evaluated when 'pyenv virtualenv-init' is run.

bin/pyenv-virtualenv-init

@@ -92,7 +92,7 @@ EOS
   ;;
 * )
   cat <<EOS
-export PATH="${PYENV_VIRTUALENV_ROOT:-${PYENV_VIRTUALENV_INSTALL_PREFIX}}/shims:${PATH}";
+export PATH="${PYENV_VIRTUALENV_ROOT:-${PYENV_VIRTUALENV_INSTALL_PREFIX}}/shims:\${PATH}";
 export PYENV_VIRTUALENV_INIT=1;
 EOS
   ;;

test/init.bats

@@ -50,7 +50,7 @@ load test_helper
   run pyenv-virtualenv-init - bash
   assert_success
   assert_output <<EOS
-export PATH="${TMP}/pyenv/plugins/pyenv-virtualenv/shims:${PATH}";
+export PATH="${TMP}/pyenv/plugins/pyenv-virtualenv/shims:\${PATH}";
 export PYENV_VIRTUALENV_INIT=1;
 _pyenv_virtualenv_hook() {
   local ret=\$?
@@ -91,7 +91,7 @@ EOS
   run pyenv-virtualenv-init - zsh
   assert_success
   assert_output <<EOS
-export PATH="${TMP}/pyenv/plugins/pyenv-virtualenv/shims:${PATH}";
+export PATH="${TMP}/pyenv/plugins/pyenv-virtualenv/shims:\${PATH}";
 export PYENV_VIRTUALENV_INIT=1;
 _pyenv_virtualenv_hook() {
   local ret=\$?