Add test() and capture() helpers to Local class

I've noticed calls to test() and capture() helper methods in run_locally block don't behave as expected.

```ruby
on(hosts) do |host|
  puts capture :echo, 'foo'
  # => foo

  puts test '[ -d ~ ]'
  # => true

  puts test '[ -f ~ ]'
  # => false
end

run_locally do
  puts capture :echo, 'foo'
  # =>

  puts test '[ -d ~ ]'
  # => test -d ~
  # on tag: 1.0.0
  #
  # => cap aborted!
  #    undefined method `verbosity' for "[ -d ~ ]":String
  #    ...
  # on HEAD

  puts test '[ -f ~ ]'
  # => [ -f ~ ]
  # on tag: 1.0.0
  #
  # => cap aborted!
  #    undefined method `verbosity' for "[ -f ~ ]":String
  #    ...
  # on HEAD
end
```

This is confusing and it is great if test() and capture() methods are also implemented in Local class.