Remove unsafe logging behavior
Added CSP headers through browser-policy package.

While Meteor/Telescope is pretty good at preventing XSS attacks, it isn't perfect. One notable example using XSS is:

[Wat][abc123]
[abc123]: javascript:alert('hao');

CSP allows you to specify origins of resources, effectively creating a policy of what scripts are allowed to be run. This effectively eradicates most if not all common XSS attacks.