Allow switches without an any block

Partial implementation and failing test

```log
  1) Switch should respect break statements
     Failure/Error: break
     LocalJumpError:
       break from proc-closure
     # ./spec/switch_spec.rb:44:in `block (4 levels) i
n <top (required)>'
     # ./lib/switch.rb:35:in `call'
     # ./lib/switch.rb:35:in `block in execute_procs'
     # ./lib/switch.rb:32:in `each'
     # ./lib/switch.rb:32:in `execute_procs'
     # ./lib/switch.rb:18:in `execute'
     # ./lib/kernel_ext.rb:3:in `switch'
     # ./spec/switch_spec.rb:32:in `block (2 levels) i
n <top (required)>'
```