Add commands to operate snapshot template

[Alexander Bozhenko]

Analogously to https://bugs.launchpad.net/fuel/+bug/1431240
We need to be able to operate snapshot template(that is predefined in DUMP in nailgun/settings.yaml [1]):
1) Export default template
2) Import custom template

Having this will allow us to have the following workflow:
1. Customer files a ticket
2. We read the description and send him snapshot template.
We probably may customize the template for every ticket, since we want to get additional info depending on what is broken.
3. Client generate a customized snapshot and send it to us.

It is important that snapshot template doesn't contain any environment-specific data, like node names.
This data is populated by DumpTaks in nailgun/task/task.py.
So we these templates will be universal and suitable for every environemnt.

[1] https://github.com/stackforge/fuel-web/blob/b1cb2f73c147c394fd6a7d91667f61859e6bc20a/nailgun/nailgun/settings.yaml#L643

[Sebastian Kalinowski (prmtl)]

But this is what exactly was achieved with https://bugs.launchpad.net/fuel/+bug/1431240 - you create a snapshot config (as it is in DUMP section of settings.yaml) and user can then create a snapshot:

 $ fuel snapshot < custom_snapshot_config.yaml

[Alexander Bozhenko (alexbozhenko)]

What fuel currently gets is config for shotgun, already populated with all nodes data.
In other words, custom_snapshot_config.yaml that you are passing is not got through DumpTask, but passed to shotgun, like if you run it directly:
shotgun -c custom_snapshot_config.yaml

[Aleksey Kasatkin (alekseyk-ru)]

Looks as a feature. Does not break anything. Moved to 8.0.

[Alexander Kislitsky (akislitsky)]

We passed SCF in 8.0. Moving the bug to 9.0.