Fix initial user creation.

sqlite3.connect automatically creates a database file if it doesn't
exist yet. Consequently, os.path.isfile will always return true, the
auth table won't be created, and inserting a user will fail.

ankisyncctl.py

@@ -69,8 +69,7 @@ def adduser(username):
         conn = sqlite3.connect(AUTHDBPATH)
         cursor = conn.cursor()
 
-        if not os.path.isfile(AUTHDBPATH):
-            cursor.execute( "CREATE TABLE auth "
+        cursor.execute( "CREATE TABLE IF NOT EXISTS auth "
                         "(user VARCHAR PRIMARY KEY, hash VARCHAR)")
 
         cursor.execute("INSERT INTO auth VALUES (?, ?)", (username, hash))