Caches tiles to Amazon S3.
Requires boto (2.0+):
"bucket": "<bucket name>",
"access": "<access key>",
"secret": "<secret key>"
S3 cache parameters:
Required bucket name for S3. If it doesn't exist, it will be created.
Optional access key ID for your S3 account.
Optional secret access key for your S3 account.
Optional S3 ACL policy for uploaded tiles. Default is 'public-read'.
Optional boolean flag for whether to use the locking feature on S3.
True by default. A good reason to set this to false would be the
additional price and time required for each lock set in S3.
Optional path under bucket to use as the cache dir. ex. 'cache' will
put tiles under <bucket>/cache/
If set to true, use S3's Reduced Redundancy Storage feature. Storage is
cheaper but has lower redundancy on Amazon's servers. Defaults to false.
Access and secret keys are under "Security Credentials" at your AWS account page:
When access or secret are not provided, the environment variables
AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY will be used