Rsync backend: allow remotes

this should allow all ssh remotes permitted by rsync. Still dubbed 'local' backend
in the code, and needs testing

use e.g. `user@host:dir/to/project/`. Don't forget the trailing slash.
Make sure opam-lib using tools don't leave stuff in /tmp
/tmp: cleanup even in case of exec()

fun thing: with the new completion you can even complete subcommands of 'opam publish'
Better yet if it doesn't leave garbage behind :)
Merge pull request #1696 from OCamlPro/cleanup-tmp

Make sure opam-lib using tools don't leave stuff in /tmp
Fixed unknown package version that could lead to parse error in ~opam/installed
Fixed version on 'switch import' of pinned  packages
completion: better on filenames, fix stderr leak
Merge pull request #1698 from OCamlPro/fix-import-pin-v

Fixed version on 'switch import' of pinned  packages
More explicit opam init message

Closes #1699
Add a script to replay cudf files and show conflicts
Fix 'inconsistent universe' message after 'opam upgrade xxx'

Closes #1701
Don't print version numbers for pinned and dev packages until they're known

ie not in the 'Updating metadata' and dl messages. They're of course still there in the
action messages. Closes #1704
Merge pull request #1705 from OCamlPro/fix-upgrade

Fixed messages on init and upgrade
Merge pull request #1706 from OCamlPro/no-misleading-versions

Don't print version numbers for pinned and dev packages until they're known
Fix typo: troobleshooting -> troubleshooting
Merge pull request #1707 from avsm/not-irish

Fix typo: troobleshooting -> troubleshooting
Remove '-r' for '--root'

This is confusing with '--rec'. Remaining one-letter global options
are '-v', '-q' for verbose and quiet, and '-y' for '--yes'

Ref #1699
Revert to the 1.1 default behaviour for PATH updates, and add an option

Ref. discussion at #1699
Merge pull request #1714 from samoht/master

Add `opam-admin rename` to rename packages in a repo
Merge pull request #1715 from samoht/master

Fix renaming of packages ...