Fix up when you pass path and when you pass the object for the newContent

    This allows user to get updated with the issued invoices.

   If Sale Invoice Transaction is already Grouped (Lettered), Cancel the related payment.

   This avoids edit already modified instances.

See merge request !293

Handle only public computers or forever closed, as other scopes are
reserved for personal or project usage.

Add the minimum hateoas support required for the cli commands:
- `slapos service list`
- `slapos service info <reference>`
- `slapos computer list`
- `slapos computer info <reference>`

To enable hateoas, complete the slapos.cfg configuration with:
```
[slapos]
master_rest_url = <proxyaddr>/hateoas
```

Also: Fix some bugs and python3 incompatibilities in slap/hateoas.py.

See merge request nexedi/slapos.core!290

libanl is part of glibc since 2001 (see
https://sourceware.org/git/?p=glibc.git;a=blob;f=ChangeLog.old/ChangeLog.12;h=adcf9081d44c06e03c3899612afba7c8c0d9b3fa;hb=HEAD#l5595)

See merge request nexedi/slapos.core!291

   This script isn't used, and every custom project might overwrite it, so no need to keep it.

   This makes management easier.

   Also increase the limit, since the default is 10

   Sample values.

This is a fixup release, as 1.6.7 was missing important changelog.

See merge request nexedi/slapos.core!285

   Sample values.

whitelistfirewall manager is locking down partition access as configured in
partition's .slapos-whitelist-firewall file by using firewalld configuration.

The md5sum of last generated partition whitelist file is used to take
decision if given rule shall be updated.

The manager supports partition setup and destruction.

Note: User id is used with netfilter owner module, as currently the sourcing
      address is not enforced to be per partition.

Despite promise failure, managers shall be executed, as often thanks to
running them, promise can be fulfilled.

    Whenever a rss feed is disabled, we can use this form to render a legacy message that changes url and pubDate once a day.

   A general warning can be issued to warn all users regardless the context. This is usefull for general mantainence or custom messages, while it is urgent inform users right the way.

Some recipes (like softwaretype) need a reference for the partition
address and in webrunner, we don't have tap interface.

/reviewed-on nexedi/slapos.core!287

Thanks to this it's possible to catch issues with firewalld

It's not used by us (controlled by supervisor), and would escape /opt/slapos
anyway.