Convert dos2unix

I just dos2unix for all files.
It should be done in early.

I confirmed all test passed before/after converting.
```
[otahi@otahiair dnsruby]$ bundle exec rake test_offline
/Users/otahi/.rbenv/versions/2.1.3/bin/ruby -I"lib" -I"/Users/otahi/.bundler/dnsruby/ruby/2.1.0/gems/rake-10.3.2/lib" "/Users/otahi/.bundler/dnsruby/ruby/2.1.0/gems/rake-10.3.2/lib/rake/rake_test_loader.rb" "test/ts_offline.rb"
Run options: --seed 39216

# Running:

.......................................................IMPLEMENT NSEC3 validation!
.............................

Finished in 30.246006s, 2.7772 runs/s, 40.2367 assertions/s.

84 runs, 1217 assertions, 0 failures, 0 errors, 0 skips
[otahi@otahiair dnsruby]$
```