try to only add when pgsql

POSTGRESQL_VERSION=9.6 was released September 2016 See if we can run it on travis

Additionally allowing failures on PHP 7.1 with mariadb MARIADB_VERSION=10.1 since it is intermittently erroring

- fixes version of HHVM being tested
- drops mariadb 5.5
- adds POSTGRESQL_VERSION=9.5 (only available with sudo enabled trusty)

Handle arbitrary whitespaces when parsing SQL in order to apply LIMIT for MS SQL Server

Merge branch 'fix/#2318-fix-listing-table-columns-when-using-external-or-os-authentication-on-oracledb'

Close #2318
Close DBAL-831

Close #2302
Close #2303

fixes #2302

Close #2287
Close #1183

- includes extended default driver connection parameter handling
- minor refactoring

fixes #1183

Close #2182
Close #2277
Close DBAL-939

- fixes platform's COMMENT ON statement support
- implements reverse engineering for column comments
- marks boolean column type commented for distinction

fixes #2182

Close #2500
Close #2497

Close #2494

Blacklist one more phpunit mock objects version

The last release is still buggy, as proven here:
https://travis-ci.org/doctrine/dbal/builds/155125956
and as confirmed here:
https://github.com/sebastianbergmann/phpunit-mock-objects/pull/324

Forward port #2484

Some packages are using symfony/console 3.0 and newer as requirement, and doctrine/dbal works well with this contstrain.