Migrate ruby from oldpackages to github and update

This commit imports the old Makefile from old openwrt feeds.
Also, the package was updated to the latest version (2.1.2).

The new version was tested in a VM with no aparent problem.
No patches needed.

I added myself as maintainer.
If possible, I would like to gain commit access.

Please, drop current ruby on oldpackages.
This package might not compile in BB as r42196 or latter is needed.