Fix malformed headers issue (#15)

Use Pug instead of Jade

Minor changes to PR

- Make sure as_image is parsed correctly
- Don't set viewport size if as_image isn't set
- Bump package version

Merge branch 'master' of github.com:Tomtomgo/phearjs

Improve behaviour under high load. Small change, big impact.

Small cleanage

Fix memory leak, minor improvement

Version 0.3.0

Added connection limiter to prevent failure due to overloading
Improved/fixed header passing to workers
Improved response on server error
Code cleanup
Version bump
Update changelog

Update README.md

Update README.md