Remove implicit eval in order to comply to CSP

Hi,

   I am currently building a small ```chrome-extension``` using oboe and Chrome is very restrictive about the __Content Script Policy__. No in line scripting, no eval either explicit or implicit is allowed.

   In order to use oboe within Chrome, I propose to remove the only bit that caused my browser to complain.

   I tend to think that it is a good practice anyway, but I would understand if there is further side effects or other good reason.

Thank you.

Aurélien