Based on the great github/gitignore project.

This commit provide the structure for unit tests.
To add a test, just create a new file in the test folder named
test_whatever.py

If anything bad append during the reception of an event, do not crash
the node. This allow a node still receiving kill signals from its
parent.

Since the two executables are really contentless, we can directly
invoque the python interpreter for the bridge and erebor. This still
assume that this is installed on each computer of the infrastructure.

Use the binaries to make sure that the imports work. There's probably
still some weird things in there, but it's a start.

This is the somewhat standard python package source organization, should
make it easier later on.

Paths are not updated in this commit, meaning that most imports will
probably fail.