Make the implemented collectors clean and remove hard coded stuff

[VincenzoFerme]

Remove:

• Hard coded environment variables
• Hard coded strings
• Not needed folders and files

Add:

• Dependency on envconsul to retrieve the environment variables
• Consul service discovery

Manage:
- Dependency by only using Godeps

Docker:

• Container go that builds a project from git and remove the dependency on golang;
• Also have Dockerfile for local development, using base container to avoid code cloning among Dockerfile, if possible

Comments:

• @Cerfoglg add some explicative comment to the code, after refactoring it.