Fix LoadError for mocha/setup

The Resque tests will no longer pass for me with this line. I get:

    /Users/tarcieri/dev/resque/test/test_helper.rb:5:in `require': cannot
    load such file -- mocha/setup (LoadError)

Removing the line fixes the issue.
Added missing require 'time' for #823

worker does not load time by default which causes iso8601 to fail and
the worker to crash. It is loaded in the tests so.
Merge pull request #894 from sideshowcoder/missing_iso_time_format

Added missing require 'time' for #823
Merge pull request #888 from tarcieri/fix_mocha

Fix LoadError for mocha/setup
Update HISTORY for 1.24.1
Bumping version to 1.24.1