Various config todos (iosystem, memory, taskmanager).
Added system configuration using Typesafe's Config library.
Implemented config TODOs.
Merge pull request #18 from citlab/config-todos

Added system configuration using the [Typesafe Config](https://github.com/typesafehub/config) library and implemented config TODOs. Closes #12.
Using curator to talk to zookeeper

see curator.apache.org for the project page

motivation:
* automatic connection management with retries and stuff
* higher-level API with a nice fluent interface
ZookeeperHelper becomes ZookeeperClient + encapsulates ZK interaction