Refactored PlanningComparisonService to make it more readable.
comparisons for: status, type, responsible.

contains some bugfixes too.
changelog.
make every attribute comparable.

for now: add project.
tests for time comparisons.
Merge remote-tracking branch 'origin/feature/rails3' into feature/magic_comparison

Conflicts:
	app/assets/javascripts/timelines.js
	app/views/timelines/_timeline.html.erb
	doc/CHANGELOG.md
changelog added. sorted.
Merge remote-tracking branch 'origin/feature/rails3' into feature/magic_comparison
bugfix. rename some due dates.
get timeline rows and cells. test status.
Adds bug spec
Implements bulk file attachment on AaA
Attaches files before saving the work package
Prevents saving a new WP on attachment change
Fixes spec
Adds changelog entry
Adds specs for update action
Adapts update's to create's attachment behavior
Adapts spec to changed update behavior
Fix compatibility with old mail configuration

Previously, the compatibility code wrongly assumed that
delivery_method was always set when using the old mail configuration
format, although it has the default value :smtp.