remove fancy quote

The curly quote in ```CHANGELOG.md``` caused rspec to fail as follows:
```
  1) RuboCop Project changelog has link definitions for all implicit links
     Failure/Error: implicit_link_names = changelog.scan(/\[([^\]]+)\]\[\]/).flatten.uniq
     ArgumentError:
       invalid byte sequence in US-ASCII
rspec ./spec/project_spec.rb:32 # RuboCop Project changelog has link definitions for all implicit links
```
As you can see from this, I'm running on OS X:
```bash
$ be rubocop -V
0.19.0 (using Parser 2.1.7, running on ruby 1.9.3 x86_64-darwin12.5.0)
```