New @Deprecated utility decorator

Logs a deprecation message on the first call of the decorated method.
New bundle installation methods & API change

- install_package: installs all the modules found in the given package folder as a bundle
- install_visiting: installs as a bundle all the modules found in the given package folder,
  if they have been accepted by a visitor method

API change:
- install_bundle now returns the Bundle object instead of the bundle ID
- ServiceEvent.get_type() is now deprecated, use get_kind() instead
Update of the tests after the API changes
Enhancement of @Deprecated

The warning message now prints the stack, to determine where
the faulty call happened.
Update of Pelix modules after the API modifications