Generalize usage of AndroidVersion instead of Api level in the SDK packages.

Platform, add-on and doc packages used to use Api Level to figure out
upgrade logic. This is replaced by AndroidVersion to properly handle
codename versions.

tools/sdkmanager/libs/sdklib/tests/com/android/sdklib/repository/TestSdkRepository.java

@@ -16,8 +16,6 @@
 
 package com.android.sdklib.repository;
 
-import com.android.sdklib.SdkConstants;
-
 import org.xml.sax.ErrorHandler;
 import org.xml.sax.SAXException;
 import org.xml.sax.SAXParseException;

tools/sdkmanager/libs/sdklib/tests/com/android/sdklib/repository/repository_sample.xml

@@ -160,7 +160,7 @@
    <sdk:platform>
         <sdk:version>Pastry</sdk:version>
         <sdk:api-level>5</sdk:api-level>
-        <sdk:api-codename>Pastry</sdk:api-codename>
+        <sdk:codename>Pastry</sdk:codename>
         <sdk:revision>3</sdk:revision>
         <sdk:uses-license ref="license1" />
         <sdk:description>Preview version for Pastry</sdk:description>