Don't assume Python scripts to be directly executable

The Python script should be passed to the Python interpreter; on some
platforms the script cannot be executed with add_custom_command, only
real executable binaries can.
Remove local testing file from distribution

ecl_local.py is used in test scripts and contain (I gather) settings
local to the developer's machines; it is not distributed in the source
repository.
Merge pull request #224 from rolk/224_python

Make Python wrapper buildable (and installable)