Removed jsyeo's dev gems. Removed unused gems.

![lol](https://lh4.googleusercontent.com/-WDENMs9-9Go/UIpQ8VtoPnI/AAAAAAAAGlw/DlGT87t_eKU/s350/123.gif)
It's good to have opinions for projects, as a set standard. Otherwise, 2 months later, someone would probably try to add back either of these gems again. 

Seeing one of them here would be an indication that 'hey, we do debugging with this for most of the team', so it would make people think twice about adding it. And if 80% of the team likes to use one, then it may deserve a spot in here. Helps a lot in on boarding newbies too.

That said, it's also fine to remove it, and keep it as a standard to install such gems globally in dev machine setup scripts (if that's something that @jsyeo is looking into).

Cheers!