Added optional use of igbinary if installed
Update ServiceProvider.php
Added missing import
Update ProjectDescriptorMapper.php
Update ProjectDescriptorMapper.php

@mvriel This sounds strange to me because it is working on my project i had tests with. But if the project descriptor is not populated with data my first version just overwritten the cache with empty values then? so maybe it will be better to clear the cache if the value couldnot be unserialized. what do you think?
Update ProjectDescriptorMapper.php
Merge pull request #1309 from siad007/patch-20

Added optional use of igbinary if installed