title: How to I install Puma on Ubuntu 16.04 with rails 2.3.5 and Ruby 1.8.7?
body: <p>I'm trying to deploy Fedena 2.3 (projectfedena.org) on Ubuntu 16.04, and its built with Ruby 1.8.7 on Rails 2.3.5. I've been able to install it and run with script/server, but now I'm trying to deploy it using Puma+Nginx and as soon as I run gem install puma 3.6.2 (any version above it requires Ruby > 1.8.7), it gives me this error. Does anyone know how i can fix it?</p>
  
  <pre><code>user@server:~/development$ gem install puma -v 3.6.2
  Building native extensions.  This could take a while...
  ERROR:  Error installing puma:
      ERROR: Failed to build gem native extension.
  
  /home/user/.rvm/rubies/ruby-1.8.7-head/bin/ruby extconf.rb
  checking for BIO_read() in -lcrypto... yes
  checking for SSL_CTX_new() in -lssl... yes
  checking for openssl/bio.h... yes
  creating Makefile
  
  make
  gcc -I. -I. -I/home/user/.rvm/rubies/ruby-1.8.7-head/lib/ruby/1.8/x86_64-linux -I. -DHAVE_OPENSSL_BIO_H    -fPIC -O2 -fno-tree-dce -fno-optimize-sibling-calls  -fPIC   -c http11_parser.c
  gcc -I. -I. -I/home/user/.rvm/rubies/ruby-1.8.7-head/lib/ruby/1.8/x86_64-linux -I. -DHAVE_OPENSSL_BIO_H    -fPIC -O2 -fno-tree-dce -fno-optimize-sibling-calls  -fPIC   -c puma_http11.c
  gcc -I. -I. -I/home/user/.rvm/rubies/ruby-1.8.7-head/lib/ruby/1.8/x86_64-linux -I. -DHAVE_OPENSSL_BIO_H    -fPIC -O2 -fno-tree-dce -fno-optimize-sibling-calls  -fPIC   -c mini_ssl.c
  mini_ssl.c:4:26: fatal error: ruby/version.h: No such file or directory
   #include &lt;ruby/version.h&gt;
                            ^
  compilation terminated.
  make: *** [mini_ssl.o] Error 1
  
  
  Gem files will remain installed in /home/user/.rvm/gems/ruby-1.8.7-head/gems/puma-3.6.2 for inspection.
  Results logged to /home/user/.rvm/gems/ruby-1.8.7-head/gems/puma-3.6.2/ext/puma_http11/gem_make.out
  </code></pre>