Add --noconfirm to makepkg call to suppress dependency prompt

pacman_aur provider fails to build a package with makepkg if the package has dependencies. 

Adding --noconfirm to makepkg options solves this problem.

Here's a failed run via test-kitchen:
```

================================================================================
Error executing action `build` on resource 'pacman_aur[redis-git]'
================================================================================


Mixlib::ShellOut::ShellCommandFailed
------------------------------------
execute[makepkg -s --asroot] (/tmp/kitchen/cookbooks/pacman/providers/aur.rb line 89) had an error: Mixlib::ShellOut::ShellCommandFailed: Expected process to exit with [0], but received '1'
       ---- Begin output of makepkg -s --asroot ----
       STDOUT: resolving dependencies...
       looking for inter-conflicts...

       Packages (2): perl-error-0.17021-1  git-1.8.5.2-1

       Total Download Size:    3.68 MiB
       Total Installed Size:   20.89 MiB
       STDERR: ==> Making package: redis-git 20111002-1 (Wed Jan  1 02:15:59 UTC 2014)
       ==> Checking runtime dependencies...
       ==> Checking buildtime dependencies...
       ==> Installing missing dependencies...
       :: Proceed with installation? [Y/n] ==> ERROR: 'pacman' failed to install missing dependencies.
       ---- End output of makepkg -s --asroot ----
       Ran makepkg -s --asroot returned 1


       Cookbook Trace:
       ---------------
       /tmp/kitchen/cookbooks/pacman/providers/aur.rb:94:in `block in class_from_file'
       

       Resource Declaration:
       ---------------------
       # In /tmp/kitchen/cookbooks/redacted/recipes/default.rb

        17:   pacman_aur 'redis-git' do
        18:     action [:build, :install]
        19:   end
        20:



       Compiled Resource:
       ------------------
       # Declared in /tmp/kitchen/cookbooks/redacted/recipes/default.rb:17:in `from_file'

       pacman_aur("redis-git") do
         action [:build, :install]
         retries 0
         retry_delay 2
         cookbook_name :"redacted"
         recipe_name "default"
         package_name "redis-git"
         builddir "/tmp/kitchen/cache/builds"
       end

```

After the fix makepkg prompts but does not wait for confirmation:

```
 * execute[makepkg -s --asroot --noconfirm] action run[2014-01-01T02:12:17+00:00] INFO: Processing execute[makepkg -s --asroot --noconfirm] action run (/tmp/kitchen/cookbooks/pacman/providers/aur.rb line 89)
resolving dependencies...
looking for inter-conflicts...

Packages (2): perl-error-0.17021-1  git-1.8.5.2-1

Total Download Size:    3.68 MiB
Total Installed Size:   20.89 MiB

:: Proceed with installation? [Y/n]
:: Retrieving packages ...
downloading perl-error-0.17021-1-any.pkg.tar.xz...
downloading git-1.8.5.2-1-x86_64.pkg.tar.xz...
checking keyring...
checking package integrity...
loading package files...

...
```