Add expiration support

[tdakkota]

#86

Defines two new interfaces:

type SetterWithExp interface {
	SetExp(k string, v interface{}, exp time.Duration) error
}

and

type Cache interface {
	Store
	SetterWithExp
}

implemented for

• Redis
• Memcached
• Freecache
• Hazelcast
• BadgerDB
• etcd

[philippgille]

Hello 👋, sorry I didn't intend to close this PR - it was automatically done by GitHub due to the deletion of the develop branch, which was the target branch of this PR. I will do some dependency updates first, and get back to this later.