Update Credentials.pm

clear_credentials called undefined subroutines with leading underscores in their names. Removed the leading underscores to that it would call the two subroutines defined right below it.
Merge branch 'pr/57'
Add files to test scripts/cpan
Ignore cpan-home, created during the tests for scripts/cpan
Update lib/App/Cpan.pm from the latest in the cpan-script repo.

This copy is now authoritative.
Clean up cpan-home, created by the tests for scripts/cpan
Remove .releaserc file
Remove old gitignore files
Remove trailing whitespace
Rename directories to tie them to the 97- tests
Move some opening braces around
Remove some notes after __END__
remove shebang lines
Make the Test::More import list a qw() to make it like elsewhere
Remove subtests for older Test::More
Remove BOM from file
Update MANIFEST for 97-* file reorganizaton
Put blocks around the code that had subtests before
Update path to test lib
Remove noisy output