Added more FakePage convenience methods

FakePage.WithContentTypeId()
FakePage.WithProperty()
FakePage.WithLanguageBranch()
Added the virtual keyword to new methods
Merge remote-tracking branch 'upstream/master'
Added FakePage.WithChildren()

Can be used to create page structure without assigning intermediate
pages to variables.
Merge pull request #2 from psst/fakepage-withchildren

FakePage.WithChildren()