Added a new binary, accounts_manager.

- Updated main Cargo.toml file
 - Created a new readme & binary
 - Includes configuration options from the validator, which now has it's config as a library.

Cargo.toml

@@ -23,4 +23,5 @@ members = [
 	"beacon_node/beacon_chain/test_harness",
 	"protos",
 	"validator_client",
+	"account_manager",
 ]