CHEF-3685: Fix rspec tests to work from the gem.

Some spec examples operate on .dotfiles. These files were missing
from the rubygems.org gem file.

Note that the fix (with FNM_DOTMATCH) correctly avoids the top-level
dotfiles because the glob operates only on subdirectories.
Don't pass directories to Gem::Specification#files.

http://rubygems.rubyforge.org/rubygems-update/Gem/Specification.html#method-i-files
"Only add files you can require to this list, not directories, etc.
Directories are automatically stripped from this list when building
a gem, other non-files cause an error."