Add dynamic wget support for fetching from http

Previously, staging::file depended on curl being available on a system
in order to fetch via http, https or ftp. This commit upgrades
staging::file to also be capable of using wget, if it can detect its
precence on a system (determined through a custom fact). If neither curl
nor wget are detected the behavior will fall back to curl, and thus be
unmodified.

In addition to the additional functionality the case statements are
cleaned up and compressed.
Update version number to 0.3.0
Merge pull request #8 from reidmv/feature_wget

Feature wget