Increase coverage

deleting this line is causing the zipping of this file to fail

```
/Users/feelobot/.gem/ruby/2.1.3/gems/archive-zip-0.7.0/lib/archive/zip.rb:353:in `basename': no implicit conversion of nil into String (TypeError)
	from /Users/feelobot/.gem/ruby/2.1.3/gems/archive-zip-0.7.0/lib/archive/zip.rb:353:in `block in archive'
	from /Users/feelobot/.gem/ruby/2.1.3/gems/archive-zip-0.7.0/lib/archive/zip.rb:352:in `collect'
	from /Users/feelobot/.gem/ruby/2.1.3/gems/archive-zip-0.7.0/lib/archive/zip.rb:352:in `archive'
	from /Users/feelobot/.gem/ruby/2.1.3/gems/archive-zip-0.7.0/lib/archive/zip.rb:87:in `block in archive'
	from /Users/feelobot/.gem/ruby/2.1.3/gems/archive-zip-0.7.0/lib/archive/zip.rb:113:in `open'
	from /Users/feelobot/.gem/ruby/2.1.3/gems/archive-zip-0.7.0/lib/archive/zip.rb:87:in `archive'
	from /Users/feelobot/.gem/ruby/2.1.3/gems/gantree-0.3.0/lib/gantree/deploy.rb:90:in `create_version_files'
	from /Users/feelobot/.gem/ruby/2.1.3/gems/gantree-0.3.0/lib/gantree/deploy.rb:23:in `run'
	from /Users/feelobot/.gem/ruby/2.1.3/gems/gantree-0.3.0/lib/gantree/cli.rb:18:in `deploy'
	from /Users/feelobot/.gem/ruby/2.1.3/gems/thor-0.19.1/lib/thor/command.rb:27:in `run'
	from /Users/feelobot/.gem/ruby/2.1.3/gems/thor-0.19.1/lib/thor/invocation.rb:126:in `invoke_command'
	from /Users/feelobot/.gem/ruby/2.1.3/gems/thor-0.19.1/lib/thor.rb:359:in `dispatch'
	from /Users/feelobot/.gem/ruby/2.1.3/gems/thor-0.19.1/lib/thor/base.rb:440:in `start'
	from /Users/feelobot/.gem/ruby/2.1.3/gems/gantree-0.3.0/bin/gantree:9:in `<top (required)>'
	from /Users/feelobot/.gem/ruby/2.1.3/bin/gantree:23:in `load'
	from /Users/feelobot/.gem/ruby/2.1.3/bin/gantree:23:in `<main>'
```