Update to latest v2 bootstrap

Downloaded from http://downloads.buildout.org/2/bootstrap.py
Fix nondeterministic test failures

This fixes three test failures I've seen on Python 3.3:

  test_allow_w_single_interface
  test_require_w_set_schema_normal_fields
  test_require_w_single_interface

All caused by dictionary iteration returning items in a different order
than the test expected.