Solution found at github
Warning:
mongodb/mongodb 1.0.2 requires ext-mongodb ^1.1.0 -> the requested PHP extension mongodb is missing from your system.
- Install mongodb
sudo apt-get install mongodb
- Add the following code in: /etc/php5/mods-available/mongo.ini
; configuration for php mongodb module
; priority=20
extension=mongodb.so
- Use the following composer command
composer require jenssegers/mongodb --ignore-platform-reqs