title: socialauth-android: proguard errors when exporting apk
body: <p>Using socialauth-android, when I try to export my project I get these warnings:</p>
  
  <pre><code>    Warning: org.brickred.socialauth.util.SocialAuthUtil: can't find referenced class javax.servlet.http.HttpServletRequest
       Warning: there were 111 unresolved references to classes or interfaces.
                You may need to add missing library jars or update their versions.
                If your code works fine without the missing classes, you can suppress
                the warnings with '-dontwarn' options.
       Warning: there were 140 unresolved references to program class members.
                Your input classes appear to be inconsistent.
                You may need to recompile the code or update the library versions.
                Alternatively, you may have to specify the option 
                '-dontskipnonpubliclibraryclassmembers'.
       java.io.IOException: Please correct the above warnings first.
          at proguard.Initializer.execute(Initializer.java:330)
          at proguard.ProGuard.initialize(ProGuard.java:212)
          at proguard.ProGuard.execute(ProGuard.java:87)
          at proguard.ProGuard.main(ProGuard.java:484)
  </code></pre>
  
  <p>Could someone help?</p>