Ignore package-delete errors

[metayan]

Demote errors to messages when trying to delete packages

[metayan]

Any errors that appear are added to the *Messages* buffer.

I also tried adding package-autoremove, but find it strange that it wants to delete so much:

12 packages will be deleted:
sublime-themes, smex, slime-company, powerline, pos-tip, paredit, neotree,
multiple-cursors, expand-region, company-quickhelp, company, ag, proceed? (y or n) n

So skipped that for now.

[Shinmera]

It shows that list because they're probably all the old versions of it. Looking at the definition of package-autoremove and co, it seems to be actually what I wanted all along, minus the prompt.