refactor
update specs2 from 1.12.2 to 1.12.3.
refactor (rename package names).

rename DefaultClient to ClientImpl.
add scaladoc.
add the method to get the space.
add the method to get the page by id.
add the method to get the page comments.
add methods to get and create a comment.
add methods to remove a comment.
remove debug output.
add methods to get attachments.