Added a vagrant definition for a caching proxy

Supports apt & rpm base repositories in addition to the puppetlabs
repositories.
Added script for checking dependencies
Added checkdeps script info to readme
Merge branch 'feature/check-dependencies' into develop

* feature/check-dependencies:
  Added checkdeps script info to readme
  Added script for checking dependencies
Now supports building of mininet images.
Merge branch 'release/0.3'

* release/0.3:
  Now supports building of mininet images.
  Added checkdeps script info to readme
  Added script for checking dependencies
  Added a vagrant definition for a caching proxy