Remove warnings

```
/Users/trsw/.rbenv/versions/2.1.3/lib/ruby/gems/2.1.0/gems/beaneater-0.3.3/lib/beaneater/connection.rb:95: warning: assigned but unused variable - e
/Users/trsw/.rbenv/versions/2.1.3/lib/ruby/gems/2.1.0/gems/beaneater-0.3.3/lib/beaneater/tube/record.rb:56: warning: assigned but unused variable - ex
/Users/trsw/.rbenv/versions/2.1.3/lib/ruby/gems/2.1.0/gems/beaneater-0.3.3/lib/beaneater/tube/collection.rb:136: warning: assigned but unused variable - res
/Users/trsw/.rbenv/versions/2.1.3/lib/ruby/gems/2.1.0/gems/beaneater-0.3.3/lib/beaneater/job/collection.rb:35: warning: assigned but unused variable - ex
/Users/trsw/.rbenv/versions/2.1.3/lib/ruby/gems/2.1.0/gems/beaneater-0.3.3/lib/beaneater/job/collection.rb:52: warning: assigned but unused variable - ex
/Users/trsw/.rbenv/versions/2.1.3/lib/ruby/gems/2.1.0/gems/beaneater-0.3.3/lib/beaneater/job/collection.rb:106: warning: assigned but unused variable - e
```