Added $wgAWSBucketDomain for custom S3 domains

[gboyers]

Added a new variable: $wgAWSBucketDomain

This enables you to use a custom S3 domain (eg files.example.com). This is particularly useful for use with a CDN like CloudFlare.

If you don't set this variable, it defaults to s3.amazonaws.com (same behaviour as current).

Also updated Readme to support users in doing this

[edwardspec]

Great stuff.

Probably not all CDNs use URL like //<bucket-name>.$wgAWSBucketDomain (it may be //<domain>/<bucket-name>), which could be solved by syntax like

$wgAWSBucketUrl = '$1.s3.amazonaws.com'; // (default)
$wgAWSBucketUrl = '$1.cdn.example.com';
$wgAWSBucketUrl = 'anothercdn.example.com/$1';

... but maybe we don't need to support those (yet). Just recording the idea for future reference.

[gboyers]

@edwardspec - I'm picking up an occasional error in the logs now:
AmazonS3FileBackend::doPrepareInternal : The unspecified location constraint is incompatible for the region specific endpoint this request was sent to. in /____/extensions/AWS/s3/AmazonS3FileBackend.php on line 522

Have checked, and LocationConstraint is usually used for the make-bucket action, shouldn't affect any GET/PUT actions.

Any ideas?

[edwardspec]

Moved into issue #7, will investigate there.