Fixed the phpdoc of the Doctrine ORM adapter
Improved the code of the DBAL adapters

- Fixed a typo in the private method name
- Added a typehint on the function argument
Simplified the Travis build matrix

Testing the older releases and the dev versions of vendors separately
and against all PHP versions is wasting the Travis resources and making
builds longer given that the number of concurrent jobs is limited.
Testing these libraries on each PHP version is not needed (they already
do it) and they can be combined in the same build.
This only going down from 20 jobs per build to 6.
Changed dependencies to stable by default for the testsuite

This also update PHPUnit to the current version rather than the old 3.7.
Fixed wrong assertion
Fixed the testing of dev versions

Instead of forcing only a few dev versions, which then require
whitelisting their own dependencies recursively in some case, the
minimum stability is altered so that semver constraint will all match
dev versions.
Merge pull request #147 from stof/patch-2

Fixed the phpdoc of the Doctrine ORM adapter
Fixed coding standards
Merge pull request #148 from stof/fix_cs

Fix coding standards
Merge pull request #149 from stof/typehint_query_builder

Improved the code of the DBAL adapters
Merge pull request #150 from stof/simplify_travis

Simplified the Travis build matrix
Added testing on HHVM
Made HHVM use dev versions of dependencies

Doctrine DBAL stable is not compatible with HHVM. Only the 2.5 version
is but it is not yet stable.
Disallow failures on HHVM
Improved some phpdoc
Merge pull request #151 from stof/hhvm

HHVM testing
Merge pull request #153 from stof/phpdoc

Improved some phpdoc
Removed the dev requirement of doctrine/mongodb-odm

This package is now added dynamically on Travis for supported PHP
versions (instead of being removed for HHVM). This avoids having a
dependency to ext-mongo when installing the dev dependencies of the
library, making it easier to run the testsuite for contributors.
Merge pull request #156 from stof/soft_mongo_deps

Removed the dev requirement of doctrine/mongodb-odm
Implement Elastica pagination support