Update query-builder.rst

->andWhere() can be used directly, without any ->where() before, and we can just always use ->andWhere(). This is why ->hasWhere() is useless, cf. #1043.
Update query-builder.rst
Merge pull request #1044 from ronanguilloux/patch-2

Use of ->andWhere() whithout any ->where() before is valid
Fix the "Erroneous data format for unserializing" error message
Merge pull request #1045 from marmotz/master

Fix the "Erroneous data format for unserializing" error message
Using `PHP_VERSION_ID` instead of `version_compare` to see if we're using PHP 5.4+
Merge branch 'hotfix/php-version-id-check-in-metadata-prototype-instantiation'
Cleanup 93c276d
Fix minor grammatical error
A few minor changes for English and clarity
Merge pull request #1047 from simonharris/master

Minor grammatical corrections
Fix wrong version
Merge branch 'master' of github.com:doctrine/doctrine2