[QA] composer based jobs migrated to Nodepool

[Antoine Musso]

Hello,

I have migrated most of the composer jobs to Nodepool disposable
instances and it is pretty much uneventful (I have triggered run for any
repos having those jobs and all passed after a few tweaks).

The jobs comes in three flavor:

 composer-php55-trusty
   Ubuntu Trusty Zend 5.5.9

 composer-hhvm-trusty
   HHVM as used on Wikimedia on Ubuntu Trusty

 composer-hhvm-jessie
   HHVM but on Jessie, which would be useful as an integration test
whenever Wikimedia migrates application servers to Jessie.


I am going to look at migrating the MediaWiki PHP jobs. The result so
far are encouraging and it should not be too much of a trouble.


-- 
Antoine "hashar" Musso