Device tracker for o2box

[chrido]

This PR adds support for the O2Box, similar to the one shown here:
https://hilfe.o2online.de/docs/DOC-1332

[rmkraus]

What happens here if host and password are not defined in the configuration?

[chrido]

fixed

[chrido]

Addressed the comments, updated to dev

[balloob]

Can you add your file to .coveragerc and it seems that CI reported some style violations: https://travis-ci.org/balloob/home-assistant/jobs/102450052#L187-L214

[balloob]

This is an automated response to help you succeed in getting this PR merged.

• Whenever CI fails, the reason for failing will be at the bottom of the log. Each Python version performs different tests so it can be that only Python 3.5 fails. Your PR cannot be merged unless CI is green!
• Always make sure your fork is up to date before you create a new branch. No "merge upstream" or "merge dev" commits. Also rebase on the dev branch before creating a PR.
• Squash your commits when the PR is ready to be merged.

If your code communicates with devices:

• Use a 3rd party library for communication. Add dependencies via REQUIREMENTS variable (example).
• Only import your 3rd party dependencies inside functions that use it (example).
• Run script/gen_requirements_all.py to update requirements_all.txt.
• Add your new files to .coveragerc

If your code does not depend on external devices:

• Write tests to verify your code works

[balloob]

Closing this PR as it has gone stale.