Add Ruby version checking to ensure using supported Rubies

nise-bosh scripts works with older rubies, but the ERB of the older rubies genarates different results from the supported Rubies.
Fix the file name of the spec for runner.rb
Add Travis config and badge
Get the current ip address using `ip` command

Some virtual machines have vnet0 as their default interface and `ifconfig` command raises an error.
Added multi job instllation support.