Merge pull request #15 from nubs/master

Add php 5.5 to travis build.
Composer update
Change my developer email
Change Spencer developer email
Merge pull request #16 from chadicus/master

Change developer email
Add newTimestamp parameter and functionality to ackSend() and requeue().

To keep up with the csharp lib.
Add prefix check to index generation.
Merge pull request #17 from gaillard/master

Add newTimestamp parameter and functionality to ackSend() and requeue(). Also add prefix check for indexes.
Add php 5.6 for travis (yay for alpha!).
Merge pull request #19 from nubs/php56

Add php 5.6 for travis (yay for alpha!).
Switch to PSR-4.
Merge pull request #20 from nubs/psr-4

Switch to PSR-4.