Fix #2115 Clean AUFS references. Also fixes some links to client libraries and mongo example.
document what `vagrant up` is actually doing

* don't mention outdated PPA that Vagrantfile doesn't use
* point to official Ubuntu installation instructions that Vagrant appears to be following; should be future proof
Merge pull request #2139 from metalivedev/2115-AUFScleanup

Fix #2115 Clean AUFS references.
Merge pull request #2144 from shamrin/patch-5

document what `vagrant up` is actually doing