Allow enabling via drush without depending on downloading first.
Merge branch 'master' into aegirvps
Complete re-factoring.

Removed dependencies on external modules. This consisted mainly of 'apt',
and 'common, which 'apt' depends on. Created an optional drush::apt class
that will provide the minimum for apt to function, but can be turned off
with a parameter to the main drush class. This makes the installation itself
optional, and should allow for better portability.

Made heavy use of a drush::defaults class to provide default arguments to
all classes and defines. Defined a general drush::run resource type to allow
running Drush commands easily and consistently. Rebuilt other resources to
wrap around drush::run.

Updated docs to describe the current functionality in lots of detail.
Fix defaults.
Provide a basic git resource, and use it to clone the source version of Drush.
Remove errant comma.
Fix lint warnings.
Add smoke-tests, and bugfixes from testing.
Add tests.
Add debug output.
Assume the Vagrantfile is symlinked from the repo root.
Support specifying the version of packages to download.
Add 'timeout' parameter for drush::run, and include defaults in init.
Rebase when pulling from git, and simplify base parameter names.
Fix errant commas.
Set backports only when installing via apt-get.
Rework how we pass backports to the drush::apt class.
Standardize resource names, and ensure they are unique.
Fix typo.
Remove apt pinning when we don't need it.