Fixes undefined index #19
#19 primary_port
showUrls option
Added autoloading

Autoloading is now done using Composers 'files' autoloading mechanism (https://getcomposer.org/doc/04-schema.md#files). This way one doesn't have to include the library everywhere it's needed. It's just "there".
Added Composer installation instructions

I've added a small installation help for Composer that should help developers to get started with REF.
If https://github.com/digitalnature/php-ref/pull/21 makes it, then using ```require``` is no longer needed in Composer driven projects. I also pointed that out in the documentation.
Merge pull request #21 from ureimers/patch-1

Added autoloading
Merge pull request #22 from ureimers/patch-3

Added Composer installation instructions
Merge pull request #20 from morrislaptop/master

#19