Fix more tests on Windows. Don't fail due to directory separator differences

I encountered the failures upon cloning from GitHub and running `dzil test`.

Specifically:

    Failed test 'Correct caller for app'
    at t\app.t line 210.
           got: 't\app.t'
      expected: 't/app.t'

    Failed test 'Correct App name from caller'
    at t\caller.t line 24.
           got: 't\caller.t'
      expected: 't/caller.t'

    Failed test 'contents ok'
    at t\dispatcher.t line 224.
    ...

So, I canonicalized the comparisons. Now, this will still cause failures if the test scripts are invoked in funny ways (e.g. `prove -b ../Dancer2\t/app.t`), but these changes should remove spurious test failures under usual build conditions.

I tried the new versions both with Strawberry Perl 5.20.1 64 bit, my custom build using MSVC, and they seem to work.