Added bunch of javadocs and restricted some visibility.

No functional changes

src/main/java/org/scribe/oauth/OAuthService.java

@@ -2,15 +2,50 @@ package org.scribe.oauth;
 
 import org.scribe.model.*;
 
+/**
+ * The main Scribe object. 
+ * 
+ * A facade responsible for the retrieval of request and access tokens and for the signing of HTTP requests.  
+ * 
+ * @author Pablo Fernandez
+ */
 public interface OAuthService
 {
+  /**
+   * Retrieve the request token.
+   * 
+   * @return request token
+   */
   public Token getRequestToken();
 
+  /**
+   * Retrieve the access token
+   * 
+   * @param requestToken request token (obtained previously)
+   * @param verifier verifier code
+   * @return access token
+   */
   public Token getAccessToken(Token requestToken, Verifier verifier);
 
+  /**
+   * Signs am OAuth request
+   * 
+   * @param accessToken access token (obtained previously)
+   * @param request request to sign
+   */
   public void signRequest(Token accessToken, OAuthRequest request);
 
+  /**
+   * Returns the OAuth version of the service.
+   * 
+   * @return oauth version as string
+   */
   public String getVersion();
 
+  /**
+   * Adds the 'scope' parameter. This is **not** a default OAuth parameter and the setting is optional.
+   * 
+   * @param scope OAuth Api scope (optional)
+   */
   public void addScope(String scope);
 }