Updated the reference to the new 'akrabat/ip-address-middleware/' rep…

…ository (#13)

Fix version lock for rka-ip-address-middleware

* Delete composer.lock;
* Edit required version of rka-ip-address-middleware.

Merge pull request #10 from DavidePastore/single-ip-usage-documentation

Add documentation about single IP usage

Closed #2

Initial release