It can exclude directories from the hash computation, which may
be handy for more than one software release.
Its first application will be to exclude logrotated logs from the signature
file, and the zodb backup, as they integrate their own integrity mechanisme

Rewrite the [runner-exporter bash script](https://lab.nexedi.com/nexedi/slapos/blob/2a01586bfe17f46e2ef26ec6e45bef692435ed28/software/slaprunner/template/runner-export.sh.jinja2) in python.

Also parametarize the signature function to not use only sha256sum which can create issues on some systems. This should be a separated commit, but that shouldn't be a blocker.

Write unit tests for the main functions of this exporter script. As every trick in the original bash script were not obvious / understood / found by me, I may have missed some.

/reviewed-on !44

This is the promise that will be used for the backupserver software release. It is working as is (with some needed changes in backupserver software release of course) but I may add more features.

I'd like to have a first review of my code.

/reviewed-on !43

check_free_disk_space is now in promise.plugin, with some improvement.
Database connection timeout is now 10 seconds
If database is locked, promise will try again 10 times before start to raise error with "database is locked" message.

promise are run by slapgrid now, monitor will collect result and generate final files
monitor runpromise script can be used to test a promise (which is implemented on the new promise design)
remove all generated script and logrotate code from monitor.py, they will be added in buildout

/reviewed-on !20

/reviewed-on !16

/reviewed-on !12

  Implement a watchdog to kill process which are hold on dead lock
  state after a greceful reload.

  taskdistribution works on failover mode if master is undefined, so it is not needed to have 2 methods

  Add new promise to check re6st is on optimal status

  Added a promise to test if there is a packet lost when ping to an IPv4/IPv6.

  Added new promise to inspect an apache error log to detect failures if failures occurred.