Missing LocationService

[socksrust]

We need a Location service, we can only add locations to Identities here:

https://github.com/GetScatter/walletpack/blob/master/packages/core/lib/services/utility/IdentityService.js

Which IMO isn't correct, as identities should only have a location ID, instead of the whole Location object.

Another options is to add a KeychainService instead of having those methods on a Keychain model:

walletpack/packages/core/lib/models/Keychain.js

Line 68 in 02d59a8

updateOrPushLocation(location){