revamped version of node-ts-cache

[boredland]

Hi there! As I didn't want to write something myself, I decided to give this a bigger overhaul.

The big changes so far:

• isLazy leads to returning the item and removing it afterwards
• items saved regularly are being saved with a redis ttl for the redis storage
• meta-data of fetched items is being returned (createdAt and if it has expired)
• coverage is being collected
• DI-style withCache factory to wrap your functions in
• afterExpired hook, so you can trigger recreations etc. if needed
• shouldCache hook, so you can decide if sth should be cached after a command ran
• dependencies cleansed
• testing using pure jest, no more assert&sinon
• superjson for json (de-)serialization
• removed lerna
• uses changeset for versioning
• tests for the elasticsearch module
• a very generic postgres module
• stuffed all tests into factories, so we can run them all for all storage modules (and fixes little issues I found doing that)
• removed isCachedForever
• moved to milliseconds for ttl

If you'd like this to be upstreamed - I'm very open to that!

[havsar]

@boredland I will have a look on this in the next days.