Renames Tracker into Type.
Fixes old migrations w/ trackers.

This adds the old tracker model to the migrations that use it. The code
for the migrations was not changed, as the const name is set to Tracker
via

  Object.const_set("Tracker", AddTrackerPosition::Tracker)

Each migration removes the Tracker constant afterwards with

  Object.send(:remove_const, :Tracker)
Improve cucumber task startup time

Allow running cucumber in the same process as Rake. This saves about
10 seconds on my machine for loading the Rails environment a second
time.

Setting RAILS_ENV=test is required, so Bundler loads Gems from the
test group. This happens in  application.rb and before the Rake tasks
are loaded. So setting the environment in the Rake task would be too
late.
Log out users with empty session activity time when session lifetime is enabled.
Always set session[:updated_at] to avoid logging out users when the administrator turns on session expiration.
Refactor session_expired? conditions.
Add changelog entry.
Set updated_at immediately after login.
Add cuke for login/logout and session lifetime.
Only set updated_at for logged in users and not for anonymous users.
Added missing spec for date helper
Merge pull request #244 from opf/feature/fix-session-lifetime

[OPF#1314] Log out users with empty session activity time when session lifetime is ...
Merge pull request #265 from opf/feature/rails3_add_missing_date_spec

Added missing spec for date helper
Settings: Change brute force settings values to integers
Authentication Settings: Add option to set password validity period
Adds migration that renames trackers to types.
Moves some issue specs to work_package specs.
Renames Tracker to Type in lib, etc. folder

This includes data loader, pdf export, email and reminder Rakefiles, as
well as a few random places that I missed before.
Updates routes from Tracker to Type.
Changes translations of Tracker to Type.