Suspend HHVM testing due to PHP 7 mode issues
Suspend HHVM testing due to PHP 7 mode issues

- Suspend HHVM testing until the following items are resolved
  - HHVM PHP 7 mode issues.
    - facebook/hhvm#7626 php 7 mode not recognized by composer as PHP 7
    - facebook/hhvm#7198 type annotations on internal functions, `expects parameter 1 to be _______, null given`
    - facebook/hhvm#7544 HHVM INI settings for PHP7 mode `php 7 is not the same as php 7.1`
  - Trusty Container issues (currently beta)
    - https://github.com/travis-ci/travis-ci/issues/6842 - MySQL socket issue on Trusty beta Container (assume fixed sometime after 1Q17)
- Add line to Force hhvm PHP 7 mode for future testing
  - HHVM fails on composer `This package requires php ^7.0 but your HHVM version does not satisfy that requirement`
  - reference for change https://docs.hhvm.com/hhvm/configuration/INI-settings#php-7-settings
BenMorel/dbal,doctrine/dbal,Tobion/dbal,stof/dbal,mikeSimonson/dbal,stof/dbal,gencer/dbal,lcobucci/dbal,kimhemsoe/dbal,lcobucci/dbal,gencer/dbal,drieschel/dbal,deeky666/dbal,deeky666/dbal,Tobion/dbal,BenMorel/dbal,mikeSimonson/dbal,kimhemsoe/dbal,drieschel/dbal,vutung2311/dbal,vutung2311/dbal,doctrine/dbal