Start adding docstrings for document module.
Add more docstrings.
Add more docstrings.
Merge branch 'master' into docstrings
Add more docstrings.
Merge commit 'refs/heads/master' into docstrings
Add docstring for set_attribute.
Merge commit 'refs/heads/master' into docstrings

Conflicts:
	dougrain/document.py
Add more docstrings.
Use correct RST markup for code in docstrings.
Add docstring form delete_link.
Add failing test for delete_link with missing rel.
Add docstrings for constructors.
Add docstrings for mutators for embedded resources.
Add docstrings for CURIE mutators.
Merge branch 'master' into fixes
Stop KeyError when deleting links for non-existent rel.
Avoid KeyError deleting embeds with wrong rel.
Change optional argument name.