title: Having an issue using Calabash-Android to resign android apk file
body: <p>I am trying to figure out what I'm missing to get calabash-android to sign an apk file. Any help is appreciated. Console log below. Currently running  Mac OS X 10.9</p>
  
  <pre><code>Last login: Thu Jan 23 09:25:44 on console
  xxxxx2m3:~ xxxxx2$ echo $ANDROID_HOME
  /Users/xxxxx2/android/android-sdk/sdk
  xxxxx2m3:Calabash_Automation xxxxx2$ calabash-android resign android-app.apk 
  /Users/xxxxx2/.rvm/gems/ruby-2.1.0@global/gems/calabash-android-0.4.18/lib/calabash-android/helpers.rb:102:in `sign_apk': private method `sign_apk' called for nil:NilClass (NoMethodError)
      from /Users/xxxxx2/.rvm/gems/ruby-2.1.0@global/gems/calabash-android-0.4.18/lib/calabash-android/helpers.rb:82:in `block in resign_apk'
      from /Users/xxxxx2/.rvm/rubies/ruby-2.1.0/lib/ruby/2.1.0/tmpdir.rb:88:in `mktmpdir'
      from /Users/xxxxx2/.rvm/gems/ruby-2.1.0@global/gems/calabash-android-0.4.18/lib/calabash-android/helpers.rb:76:in `resign_apk'
      from /Users/xxxxx2/.rvm/gems/ruby-2.1.0@global/gems/calabash-android-0.4.18/bin/calabash-android:107:in `&lt;top (required)&gt;'
      from /Users/xxxxx2/.rvm/rubies/ruby-2.1.0/bin/calabash-android:23:in `load'
      from /Users/xxxxx2/.rvm/rubies/ruby-2.1.0/bin/calabash-android:23:in `&lt;main&gt;'
      from /Users/xxxxx2/.rvm/gems/ruby-2.1.0/bin/ruby_executable_hooks:15:in `eval'
      from /Users/xxxxx2/.rvm/gems/ruby-2.1.0/bin/ruby_executable_hooks:15:in `&lt;main&gt;'
  xxxxx2m3:Calabash_Automation xxxxx2$ android
  xxxxx2m3:Calabash_Automation xxxxx2$ calabash-android build android-app.apk 
  No keystores found.
  Please create one or run calabash-android setup to configure calabash-android to use an existing keystore.
  xxxxx2m3:Calabash_Automation xxxxx2$ calabash-android setup
  Please enter keystore information to use a custom keystore instead of the default
  Please enter keystore location
  
  Please enter the password for the keystore
  
  Please enter the alias
  
  Saved your settings to .calabash_settings. You can edit the settings manually or run this setup script again
  xxxxx2m3:Calabash_Automation xxxxx2$ 
  </code></pre>
  
  <p>Any help would be appreciated. This has been frustrating me for a while.</p>