* Fixes an issue where tab completing specs that start with the same
words(s) makes tab completion freak out and stop working.
* The con is that we'll see "_spec.rb" in the output, like:
```zsh
$ rspec spec/models/
models/calendar_spec.rb
models/event_closer_spec.rb
...
```
https://github.com/ggreer/the_silver_searcher
* ag is faster than ack
* ag searches all files by default (but still ignores gitignored files). This
removes the need for ack's `--type-add=` options.
* The command is 33% shorter than ack!
