Remember and apply default ACL settings to records

[cheungpat]

When implementing #126, the SDK should remember the settings and apply default ACL settings to record when needed (see below). The default ACL settings does not need to persist across application relaunch because it is expected that the developer will always call this function when the app launches.

The default ACL should not be applied to a record when it is instantiated. The default ACL should only apply when the the developer tries to mutate the record ACL.

When default ACL for the record type is not defined, the fallback ACL will apply. The fallback ACL is public-readable.

If record ACL is null, getting the record ACL will not cause the record ACL to change. Return the default ACL or fallback ACL in this case.

depends on #126