[setup.py] Add aliases.ini to sonic_installer package (#1088)

Ensure aliases.ini gets installed with the sonic_installer package to enable backward-compatibility with the versions of subcommands which contain underscores.

This was missed in #983

Author: jleveque

setup.py

@@ -59,6 +59,7 @@
     ],
     package_data={
         'show': ['aliases.ini'],
+        'sonic_installer': ['aliases.ini'],
         'tests': ['acl_input/*',
                   'mock_tables/*.py',
                   'mock_tables/*.json',