documented parameterised events
fixed typo
implemented inline before/after callbacks for events
invoke callbacks in the context of record
Append callbacks instead of overriding them.
Improved tests coverage
fixed and improved spec coverage for befire/after callbacks
fixed after callback spec
fixed event specs
Breaking changes: success/error callbacks called in context of record, not with record as argument.
Refactored callbacks in event.rb, added support for inline definition of success/error callbacks.
fixed errors catching/raising
document error callback behaviour
improved descrtiption
Merge branch 'stiff-master' into master_merge_stiff

Conflicts:
	README.md
	lib/aasm/supporting_classes/event.rb