Update protection of private classes from direct use

[lbetz]

fixes #333

[baurmatt]

Can't we just use assert_private?

[lbetz]

Pretty good idea. We started with a much earlier version of stdlib without this function. Now we've a dependency on version 4.16.0... but I'm not sure that will fix the unit tests.

[baurmatt]

This is also a major improve when it comes to the icinga2::object class. The defined() variant is a lot slower then assert_private(). This is especillay import for setups which might include hundreds/thousands of icinga2::object's.

[baurmatt]

The problem with the tests is, that the assert_private() needs to be fake. This should do the trick:

  before(:each) do
    # Fake assert_private function from stdlib to not fail within this test
    Puppet::Parser::Functions.newfunction(:assert_private, :type => :rvalue) { |args|
    }
  end

[lazyfrosch]

Thanks @baurmatt, I incorporated your example