Hasher in client config is unusable

[skinass]

type Config struct {
	Hasher     hasher
        ...

type hasher interface {
	update(servers []*server)
	getServerIndex(key string) (uint, error)
}

now Hasher should implement an interface with private methods with private types like *server so the only way to define a Hasher is to use a NewModuloHasher() function.

the problem is that Hasher field is public, but i cant really use it.

i purpose to change the interface this way:

type Hasher interface {
	Update(servers []strings)
	GetServerIndex(key string) (uint, error)
}

this will let us to make custom implemenation of Hasher interface

[saschat]

Sounds good. PR is welcome.