refs #7970 - don't let Ruby alternative switch to 1.9 on Ubuntu 12.04
By setting the Ruby alternative to manual mode, installation of the Brightbox version of Ruby won't automatically change the symlinks to point at ruby1.9.1.
This ensures other applications, including hammer, work as 1.8's the expected default version.
refs #7970 - don't let Ruby alternative switch to 1.9 on Ubuntu 12.04
By setting the Ruby alternative to manual mode, installation of the Brightbox
version of Ruby won't automatically change the symlinks to point at ruby1.9.1.
This ensures other applications, including hammer, work as 1.8's the expected
default version.