Added ScaleDrone to the list of Websocket PaaS
Update README.md

Included Layervault & InvisionApp
Update README.md
System Monitoring providers

Add new tools
New DNS providers
New VPS providers
Add Vagrant
Fix Saucelabs description
Rename "Pivotal" to "Pivotal Tracker"
Add URL for Fabric
Added GAE to PaaS section
Added Sendwithus to transactional email section
Add more details to Integrity and CruiseControl
Updated some links to services
Add StackLead and clean up prices in Sales Tools section
add odesk url and other useful places to hire freelancers
add missing link for Fabric deployment toolset
add Pretty Tracker Google rank monitoring service
Added Keen IO to Business & Traffic Analytics
Adding link to Slack