Some environnement like Spark do not send the argument with only one
dash. Allow the MPI_EXECUTOR to send arguments with the full name.

Because on broadcast a regex is given in dest field. And the problem
resolved by the previous commit only touched the command field.

Because we are building regex from random strings, we need to escape
them.

When a node die TakTuk may trigger two different messages, internal data
structures need protection to avoid accessing an already handled error.

Isengard still contains bits of code that are not valid, mostly stuff
about variables that were deleted some time ago but are still being
accessed.

Hopefully this is one of the last ones.

To allow the creation of a new connector, we need to extract every
uncesseray files/code from the isengard folder. This way, creating a new
connector will be to provide an other isengard_like folder with only
specif stuff.

This is more in line with the way the logging module is meant to be
used.
We still need to create new objects in a few places (entry points) and
propagate the config to newly created processes elsewhere.

This is still missing module filtering that was working before. I will
create a new issue for that.

Closes #11

Text output by a hosted message may not be in UTF8. This is not the case
for TakTuk or our controlled programs. Callback from isengard now send
the content of the gathered output in binary and utf8 form.
When the output of a subprocess is gathered for the root node, it is
encoded in bas64. On the root, the user should take care of the final
encoding. The Executor task is now able to deal with other encoding than
UTF-8.

The argument for debug level is on string type. No need to convert it.

Need to port socket_bridge too.

Logs for subprocess without catching line object where printing twice.
This commit remove the unecessary printing and just leave a color
difference.

3 options allow to control the logs :

--debug= one in erebor", "network", "isengard", "wrapper", "unix_socket", "bridge", "mpi"
--debug-level=one in NOTSET|DEBUG|INFO|WARNING|ERROR|CRITICAL
--debug-file= a file path

Need to check if sub-erebors logs are well printed to the root.

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.