utils: improve download manager

- tests are separated from package
- add the possibility to give the server file path into the url
cli: fix the remote commands

Args were expected even for the remote command update
utils: fix the package parser

If a package dependency was declared with eg vle (>=1.1), an error occurred
due to the missing patch.
utils: fix names and urls in RemoteManager

- add the missing 'pub' directory into the default remote url of
  vle.conf.
- move local.pkg and remote.pkg into the correspondind pkg dir (eg.
  pkgs-1.1).
- rename the 'packages' file expected onto a remote with 'packages.pkg'.
utils: rename the mPackages member in RemoteManager.

- mPackages is renamed mResults since it represents the results of the
  last command.
- comments are added.
utils: fix the update action in RemoteManager

The remote member was not filled with the results of the command.
cli: fix help for remote manager

Commands 'install package' and 'install source' are respectively
'install' and 'source'.
utils: fill the actionSource function in RemoteManager

Download of the source is now provided, file is not unzipped.
utils: use tar.bz2 and fill actionInstall in RemoteManager

- replace zip archive with tar.bz2 (in order to use Path::decompress) in
  actionSource.
- fill actionInstall, the dependencies are not installed yet.
cli: add user messages in RemoteManager

- add management of errors of remote commands.
- add user messages to the console for vle cli.
utils: fix actionUpdate results in RemoteManager

- the PackageIdUpdate operator is fixed.
- the results of the update command is filled with packages with newer
  versions.
- the error is managed by filling mHasError and mMessageError.
utils: fix install in RemoteManager

- the more recent version of the package is installed.
- one checks if the package is already installed.
utils: update show commands in RemoteManager

- add a localshow command, the show command now only show packages from
  remotes.
- the argument of these command is the name of packages.
- update help pages.
utils: add messages and log on install in RemoteManager

These logs are for the moment the only way to check if an install
failed.
gvle: add the adjustment and zoom management

When switching the view type from "complete" to "simple" and reverse,
the zoom setting is keep. And the adjustment of diagram inside the
graphical view is keep also. By the way, each coupled model manage its
own zoom and adjustments. (Closes #110)