Update info.rake to be able to run successfully on SuSE.

The rake task gitlab:env:info fails on a SuSE Linux system. 

I updated the task to allow for suse systems to be detected.

The failing line was os_name.squish! on line 18 (with this patch, 15 without), os_name was nil so squish! was failing, thinking it may be better to refactor this a skosh to say:

> os_name = "unknown".red
> os_name ||= run("lsb_release -irs")

To allow for Linux distributions that lack the lsb_release command to work. And then changing the puts line later to:

> puts "System:\t\t#{os_name}

I can submit that as a refactoring separately if desired. But this works as-is. No other changes were made to get things running on SuSE 11. Note I haven't tested what run() outputs when nothing is there yet, just offering it up as an idea.

Output on a SuSE 11 service pack 2 system after the change:

> bundle exec rake gitlab:env:info RAILS_ENV=production --trace
> ** Invoke gitlab:env:info (first_time)
> ** Invoke environment (first_time)
> ** Execute environment
> ** Execute gitlab:env:info

> System information
> System:		SUSE Linux Enterprise Server 11 (x86_64) VERSION = 11 PATCHLEVEL = 2
> Current User:	gitlab
> Using RVM:	no
> Ruby Version:	1.9.3p327
> Gem Version:	1.8.23
> Bundler Version:1.2.3
> Rake Version:	10.0.1

> GitLab information
> Version:	4.0.0
> Revision:	c68540e
> Directory:	/infra/app/gitlab/gitlab
> DB Adapter:	postgresql
> URL:		http://hostname
> HTTP Clone URL:	http://hostname/some-project.git
> SSH Clone URL:	git@hostname:some-project.git
> Using LDAP:	no
> Using Omniauth:	no

> Gitolite information
> Version:	v3.04-42-g2d29cf7
> Admin URI:	git@localhost:gitolite-admin
> Admin Key:	gitlab
> Repositories:	/infra/app/git/repositories/
> Hooks:		/infra/app/git/.gitolite/hooks/
> Git:		/usr/bin/git