add pre_event for all http method
add test for pre_event
New changelog format: 'new', 'update', 'fix'.
Merge branch 'develop' of https://github.com/dccrazyboy/eve into dccrazyboy-develop

Conflicts:
	eve/methods/common.py
	eve/methods/post.py
	eve/methods/put.py
on_pre_<method> docstrings.
[new] 'pre_<method>' event hooks.
Merge branch 'dccrazyboy-develop' into develop
'on_<method>' hooks renamed to 'on_post_<method>'.