Following upstream fix

  - The callback fix can potentially be backwards incompatible, will
    need to run tests on both the future version and the current version
    at some point.
Lock down the required version.

  - There are a few too many incompatibilities between the current
    version and the next version.  Going to stick with the current one
    until the changes for 0.4 are finalized before migrating towards
    that.
Remove pmr2.testing as requirement

  - pmr2.z3cform now contains the form testing helper related classes
    that are used for testing forms and requests that inherit from this
    package.
Need that zcml definition.