Hands on: Complete tests and implement a working solution for `find_maxima`

[pberkes]

Go to the directory hands_on/local_maxima_part2 and write a working implementation of the find_maxima function from slide 5:

• The module test_local_maxima contains tests corresponding to the examples on slide 6. Complete the last two test with the last examples in slide 6.

• Write the implementation of the find_maxima function in the module local_maxima (you can start from the version you had before), running the tests as you go until you have code that makes all tests pass.

• Clean up the code until you are happy, making sure that the tests continue to pass