Suport Sugar versions as a proxy for the Kernel

This provides a Sugar\Manager that will make use of a Sugar\Finder\Finder to
find a sugar based on a given path.
Sugar\Manager will give you a proxy so that you can mock all Sugar calls based
on their versions. This will allow us to work faster providing just the changes
of each version and keep the same functionality on the commands (being version
agnostic as much as possible).
Keep in mind that you can still check for the Sugar Version to make special
cases on your commands.
Merge pull request #48 from alias-mac/sugar-finder

Initial draft to support Sugar versions as a proxy
Add support to other bootstrap levels (fixes #43)
Merge pull request #44 from jcsmorais/bootstrap-levels

Add support to other bootstrap levels (fixes #43)