Use new saved endpoint for wiki parts

[Sergio Schvezov]

snapcraft update allows to bring in a cache of parts, we use this instead of polling the wiki for every part

[Impact]

 * Right now the use of wiki parts is inefficient.
 * There is a new cloud infrastructure for parts that can be used to improve the experience.
 * This should be transparent for users. However, the source for parts changes to https://wiki.ubuntu.com/snapcraft/parts and the format is different too.

[Test Case]

 * define a snapcraft.yaml that uses a part from the wiki.
 * run snapcraft, install the snap and execute it.

[Regression Potential]

 * This could affect all existing projects using the wiki. We have a suite that exercises the remote parts, but some exploratory would be good.

[Sergio Schvezov (sergiusens)]

https://github.com/ubuntu-core/snapcraft/pull/590

[Steve Langasek (vorlon)]

Hello Sergio, or anyone else affected,

Accepted snapcraft into xenial-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/snapcraft/2.12 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, and change the tag from verification-needed to verification-done. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed. In either case, details of your testing will help us make a better decision.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance!

[Leo Arias (elopio)]

Tested in an up-to-date xenial:

- enabled -proposed
- update snapcraft-parser to 2.12
- made a snapcraft with a cloud part
- snapcraft update
- snapcraft <- it works using the new endpoint.

I'm going to mark this as verified, thanks Steve!

[Chris J Arges (arges)]

The verification of the Stable Release Update for snapcraft has completed successfully and the package has now been released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.