Rail Application Error when using Heroku create command

I am following a heroku tutorial where I created my rails app. I was asked to use Heroku to get my app live online. I followed the steps for linking my Github account to Heroku via the SSH key. However when I use the command heroku create and then copy past the link provided, in this case http://ift.tt/2jPQphW, I get an "Rail Error" in the browser.

I tried to re-install Rail Bundler on my Terminal, but it shows me this error at the terminal:

System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/bin/ruby
extconf.rb
creating Makefile

make "DESTDIR="
compiling generator.c
In file included from generator.c:1:
In file included from ./../fbuffer/fbuffer.h:5:
In file included from
/Applications/http://ift.tt/2lcpfyW:
/Applications/http://ift.tt/2jPJoxO:
fatal error: 'ruby/config.h' file not found
#include "ruby/config.h"
         ^
1 error generated.
make: *** [generator.o] Error 1


Gem files will remain installed in
/var/folders/_6/fz7ndk694653_hs9h_lzmylm0000gn/T/bundler20170205-15720-1grkdr4json-1.8.6/gems/json-1.8.6
for inspection.
Results logged to
/var/folders/_6/fz7ndk694653_hs9h_lzmylm0000gn/T/bundler20170205-15720-1grkdr4json-1.8.6/gems/json-1.8.6/ext/json/ext/generator/gem_make.out

An error occurred while installing json (1.8.6), and Bundler cannot
continue.
Make sure that `gem install json -v '1.8.6'` succeeds before bundling.