Added parent page field to copy form and template
Allow changing the parent page when copying
Adapted and added tests for copying pages
Added another test for #838

This tests that the page is copied to the different parent when a
different parent is selected.
Changelog and release note for #838
Added Timo Rieber to contributors
Merge branch 'pr-838'

Conflicts:
	CHANGELOG.txt
	CONTRIBUTORS.rst
	docs/releases/0.9.rst