Fixes issue #156

Here is sample output, which fails because ENV variable for PORT is not set (intentionally)

root@daisy:~# docker run -it dokku/cf01:release /start 
+ pmsgr=/tmp/pmsgr
+ rm -f /tmp/pmsgr
+ mkfifo /tmp/pmsgr
++ cut -f1 -d=
++ env
+ for var in '`env | cut -f1 -d=`'
+ echo 'env[BUILDPACK_URL] = $BUILDPACK_URL'
+ for var in '`env | cut -f1 -d=`'
+ echo 'env[HOSTNAME] = $HOSTNAME'
+ for var in '`env | cut -f1 -d=`'
+ echo 'env[TERM] = $TERM'
+ for var in '`env | cut -f1 -d=`'
+ echo 'env[PATH] = $PATH'
+ for var in '`env | cut -f1 -d=`'
+ echo 'env[GIT_REV] = $GIT_REV'
+ for var in '`env | cut -f1 -d=`'
+ echo 'env[PWD] = $PWD'
+ for var in '`env | cut -f1 -d=`'
+ echo 'env[HEROKU_BUILD_TIME] = $HEROKU_BUILD_TIME'
+ for var in '`env | cut -f1 -d=`'
+ echo 'env[SHLVL] = $SHLVL'
+ for var in '`env | cut -f1 -d=`'
+ echo 'env[HOME] = $HOME'
+ for var in '`env | cut -f1 -d=`'
+ echo 'env[_] = $_'
+ export DOCUMENT_ROOT=
+ DOCUMENT_ROOT=
+ export INDEX_DOCUMENT=index.php
+ INDEX_DOCUMENT=index.php
+ export NGINX_INCLUDES=
+ NGINX_INCLUDES=
+ '[' -n '' ']'
+ erb conf/nginx.conf.erb
+ erb conf/site.conf.erb
+ read exitproc
+ nginx -p /app/vendor/nginx -c /app/vendor/nginx/conf/nginx.conf
+ php-fpm -p /app/vendor/php
nginx: [emerg] invalid number of arguments in "listen" directive in /app/vendor/nginx/conf/nginx.conf:71
+ echo nginx
+ echo 'Boot failed: nginx'
Boot failed: nginx
+ exit 1