Dump-time options to include/omit associations

This reverts commit ce3cfefb9a55b050f8cb8b579b425cf80318fe44.

Conflicts:
	lib/replicate/active_record.rb
Tests for custom dumping and loading
Check arity before calling dump_replicant
More descriptive instance variable in AR
Merge pull request #25 from iangreenleaf/method_redefine

Backwards compatibility for dump_replicant