Improve network performance for VirtualBox

Without those lines, VitrualBox machines are being very slow with all network operations (tested only in OS X Lion, but they are supposed to work everywhere). See https://github.com/mitchellh/vagrant/issues/1807
Add proper bash completion for "docker push"
Fix contrib/mkimage-debian.sh apt caching prevention
Insert popularity and boost docs results.
use empty string so TempDir uses the OS's temp dir automatically (Closes #2117)
Use correct auth config when logging in.
fix rm -v
Fix some error cases where a HTTP body might not be closed

Refs #2126
Make sure to close the network allocators
Fix #2115 Clean AUFS references. Also fixes some links to client libraries and mongo example.
Update AUTHORS
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* don't mention outdated PPA that Vagrantfile doesn't use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 #1956 from tianon/bash-completion

Add proper bash completion for "docker push"
replace panic by log.Fatal in tests
Merge pull request #2127 from titanous/close-body

Fix some error cases where a HTTP body might not be closed
Clean up javascript comment.
Merge pull request #2114 from metalivedev/2113-searchbump

Fix #2113 improve doc search results
Merge pull request #2145 from dotcloud/remove-panic-test

* Runtime: replace panic by log.Fatal in tests
Merge pull request #2133 from dotcloud/improve_tests

Make sure to close the network allocators
Merge pull request #2119 from SvenDowideit/2117-hardcoded-tmp-dir

use empty string so TempDir uses the OS's temp dir automatically (Closes...