more tests for holmes.worker
Worker class properly tested
Worker working
Workerstate
Handlers all working
Workers working now
Event bus
New image requests validator

Added Image Facter
New CSS requests validator

Added CSS Facter
New JavaScript requests validator

Added JS Facter
Added Validator: Image without alt attribute (Closes: #6)
Added Validator: Anchors without any text (Closes: #5)
New Meta Tags validator

Added Meta Tags Facters
Added Validator: Page without meta tags
Added Validator: Meta Robots with value of {noindex, nofollow}

Closes: #7
Added Validator: Required meta tags (Closes: #4)
Fixed toredis dependency