Centralize dependencies

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>
Implement download/upload functions

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>
Add gcc testbuild script

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>
Add clang testbuild

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>