If you would like to work on an low version ADT, you may degrade your ADT.
Eclipse->Help->About Eclipse Platform->Installation Details->Unstall all Android relevant items
Download ADT for your SDK version.
Install ADT as the offline mode.
It's OK.
If a project is created with the error proguard.cfg (No such file or directory), you may copy the 'proguard.cfg' in the Android source project to the asked path.