Merge branch 'feature/clientid' of https://github.com/ethersphere/eth-go into ethersphere-feature/clientid

typo, duplications

- remove clientstring handling from ethutil.Config
- ReadConfig takes no Identifier argument
- members Ver, ClientString, ClientIdentifier removed from Config
- type ConfValue removed
- expose public type ethutil.ConfigManager
- Set -> Save(key string, value interface{}) now takes any value to allow for persisting non-string values directly
- TODO: eliminate all eth specific configs, just a wrapper around globalconf

Note, this utility function has to move elsewhere

Feature/keys