Disable SSL cert verification when using RVM.

This should mostly only be used when gitlabhq and gitlab-shell are
on the same physical machine.

Using rvm, when running ./bin/check the following error occurs:
```
Check GitLab API access: /home/git/.rvm/rubies/ruby-1.9.3-p385/lib/ruby/1.9.1/net/http.rb:799:in `connect': SSL_connect returned=1 errno=0 state=SSLv3 read server certificate B: certificate verify failed (OpenSSL::SSL::SSLError)
	from /home/git/.rvm/rubies/ruby-1.9.3-p385/lib/ruby/1.9.1/net/http.rb:799:in `block in connect'
	from /home/git/.rvm/rubies/ruby-1.9.3-p385/lib/ruby/1.9.1/timeout.rb:54:in `timeout'
	from /home/git/.rvm/rubies/ruby-1.9.3-p385/lib/ruby/1.9.1/timeout.rb:99:in `timeout'
	from /home/git/.rvm/rubies/ruby-1.9.3-p385/lib/ruby/1.9.1/net/http.rb:799:in `connect'
	from /home/git/.rvm/rubies/ruby-1.9.3-p385/lib/ruby/1.9.1/net/http.rb:755:in `do_start'
	from /home/git/.rvm/rubies/ruby-1.9.3-p385/lib/ruby/1.9.1/net/http.rb:744:in `start'
	from /home/git/gitlab-shell/lib/gitlab_net.rb:47:in `get'
	from /home/git/gitlab-shell/lib/gitlab_net.rb:27:in `check'
	from ./gitlab-shell/bin/check:11:in `<main>'

```

for some reason, solutions posted across the net (such as setting http.ca_path and http.ca_file) don't work.