List more `snap changes`

[Ads20000]

Currently `snap changes` only lists a few changes that snappy has made to the system (last two installs only?), it should list more and/or there should be a flag for listing more.

https://askubuntu.com/questions/1035109/how-to-see-history-of-snap-packages-updates#comment1684830_1035109

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: snapd 2.32.8+18.04
ProcVersionSignature: Ubuntu 4.15.0-20.21-generic 4.15.17
Uname: Linux 4.15.0-20-generic x86_64
ApportVersion: 2.20.9-0ubuntu7
Architecture: amd64
CurrentDesktop: communitheme:ubuntu:GNOME
Date: Thu May 17 03:14:44 2018
InstallationDate: Installed on 2017-08-03 (286 days ago)
InstallationMedia: Ubuntu 17.04 "Zesty Zapus" - Release amd64 (20170412)
SourcePackage: snapd
UpgradeStatus: Upgraded to bionic on 2018-04-22 (24 days ago)

[John Lenton (chipaca)]

The changes are garbage-collected after a certain time, or after a certain number of changes, both of which are hard-coded.

If there's a bug it's in the hardcodedness of this :-)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.