v0.6.0

The 0.6.0 release contains some Breaking Changes wrt the 0.5.x branch. Here's the full summary:

• [BC] Dropped PHP 5.5 support
• [BC] Scrapped "Nonce" feature. Replayed message detection has nothing to do with HMAC and can be safely avoided if the API is served over HTTPS (if not, the user can still implement a dedicated Inspector and hook it into the Verifier).
• [BC] Scrapped response signing and verification capabilities. This is due to the realization that no PSR-7 response implementation is an accurate representation of the final HTTP response (i.e. any call to echo or header will alter the final response but not the PSR-7 object, thus it is a pointless exercise).
• Bugfix: verification now works for PSR-7 implementations that return header names in FastCGI format - see tests/EdgeCases/SlimTest.php.
• Trimmed a lot of unnecessary files from the dist package - see .gitattributes.
• Additional supported implementations - kambo/httpmessage, mibadger/http, windwalker/http (formerly asika/http).