Remove mocha deprication warnings
Rename Query class to LiveDataQuery

The name is to generic and conflicts with the a historic data query.
Extract live_data_query proxy behaviour into module

This will make it easier to later add new queries for other APIs.
Renamed instance variable of Prtg::Query

@query_hash => @query
Put request for Client to query and changed api

Client.live_data(content) is now Client.live_data.content(c)
Rename Client#live_data and LiveDataQuery

The naming wasn't appropriate. Now the new Client#table replicates
the real api behind the abstraction.

Now also the api url is part of the query.
Add Client#historicdata api
Improve readme file

- Add api url by what is implemented and what not.
- Add Changelog for v0.1.0
- Add usage examples
Bump version to 0.1.0