update docs - disabling prepared statements is not connected to managing connections externally [ci skip]

Support postgresql partitioning by making INSERT RETURNING optional

Active Record should be lazy loaded and this pull request
forced Active Record to always be loaded after initialization.

This reverts commit 8cd14c0b, reversing
changes made to 2f0c8c52.

Shadowing variable warning removed

Remove old sqlite adapter

The latter doesn't render as code in HTML output.

Regex used in Rubymine to locate the latter form:

    (\+)(:*\w+:(?::|\w)+)(\+)

remove calls to deprecated find(:first) in actionpack test suite