shelve: new output format for shelve listings
Use a more condensed and mercurial-like output format for shelve listing.
We don't prefix the message with 'shelved from...' anymore as our default
name contains the branch name or the user used his own name. To avoid
just printing the last commit message, we drop writing the description
to stdout.
old output:
default [1s ago] shelved from default (
01ba9745): create conflict
new output:
default (1s ago) create conflict
(binary:application/octet-stream)