Convert protected_parent to be an in-house gem

This commit takes a fork of protected_parent and updates it to a gem
structure.

The main difference between this version and the public
version is introducing a global constant PROTECTED_PARENT which allows
its core functionality to be overridden.

This required an additional text example which has been added.  Aside
from that the test examples have been cleaned up.

[8213]
Remove unused Rakefile

This commit removes the Rakefile which was not being used.
Removed copy/paste 'has_breadcrumb' from gemspec.
Merge pull request #1 from sqm/8213-convert-protected_parent-into-a-gem

#8213 - Convert protected_parent plugin to an in-house gem