Change the method name to get command according to specinfra#149
Change the method name to call specinfra
No more need to include detect_os
Change OS family name to lower case
Change package_installed to package_is_installed
Set OS family by set method.

No more OS helper class now.
Fix file resource type to pass specs
Fix indent
Fix cron to pass the spec
Fix routing table related things
Fix default_gateway to pass the spec
Fix group type to pass the spec
Fix host type
Fix interface but pending spec because base command class does not
implement them
Move specs from type to type/base
Fix iptables
Fix kernel_module
Fix LXC
Fix mail alias
Fix package