Add cpu_temp property to fritz status

[1RandomDev]

I added the cpu_temp property that returns an integer with the current CPU temperature and the call_http_query() method that lets you do custom requests to the query.lua endpoint.

[kbr]

Thanks for your contribution, providing another URL for queries. At least by the interface-documentation from AVM this seems not to be covered. Do you have any references?

Then there are some issues (beside a minor PEP 8) with the code: in the FritzConnection class the aha-interface is owerwritten, the cpu-temperature is returned as string instead as a number and there is a lot of code-duplication.

From my point of view the integration of a third query-endpoint needs some refactoring in the existing code.

For future pull-requests I have created a new development-branch at github.