Remove examples

[krichardsson]

When the client was split into client and crazyflie-lib-python, the examples directory ended up in both projects. The one in this project should be removed as the examples show how to use the library.

[krichardsson]

There are some ZMQ examples that should be kept. Remove the rest.

[krichardsson]

Oups, wrong issue number in the commit comment. 972e346 fixes this issue.