core: added basic chain configuration

Added chain configuration options and write out during genesis database
insertion. If no "config" was found, nothing is written to the database.

Configurations are written on a per genesis base. This means
that any chain (which is identified by it's genesis hash) can have their
own chain settings.

core/vm/vm_jit_fake.go

@@ -22,5 +22,5 @@ import "fmt"
 
 func NewJitVm(env Environment) VirtualMachine {
 	fmt.Printf("Warning! EVM JIT not enabled.\n")
-	return New(env, nil)
+	return New(env, Config{})
 }