quiet plugin unzipping

[akosyakov]

It is very verbose right now:

root INFO unzipping the plugin ProxyPluginDeployerEntry {
  deployer:
   PluginVsCodeFileHandler {
     unpackedFolder:
      '/private/var/folders/h2/m_txl3zj69x8nnhqmj03r2000000gn/T/vscode-unpacked' },
  delegate:
   PluginDeployerEntryImpl {
     originId: 'local-dir:../../plugins',
     pluginId: 'codezombiech.gitignore-0.6.0.vsix',
     map: Map {},
     changes: [],
     acceptedTypes: [],
     currentPath:
      '/Users/vincentfugnitto/workspace/theia/plugins/codezombiech.gitignore-0.6.0.vsix',
     initPath:
      '/Users/vincentfugnitto/workspace/theia/plugins/codezombiech.gitignore-0.6.0.vsix',
     resolved: true,
     resolvedByName: 'LocalDirectoryPluginDeployerResolver' },
  deployerName: 'PluginVsCodeFileHandler' }

We don't need to see the whole json object. It should b replaced by one liner, something like unzipping such id in the following folder.