Fixes download.sh: Check cached archive integrity.
Fixes download.sh: Move archive content to intermediary folder, remove duplicated folder structure.
Fixes download.sh: Exctracted download to function, improves flow.
Fixes download.sh: Some minor code formatting.
Fixes download.sh: Minor output clean-up
Merge pull request #252 from eliasdorneles/master

Fixes download.sh: Minor output clean-up