Add Galaxy lib directory to Python path for 2 scripts

Also fix check introduced in commit 0763cab37a .

Fix https://github.com/galaxyproject/galaxy/issues/5722 .

scripts/cleanup_datasets/admin_cleanup_datasets.py

@@ -53,6 +53,8 @@ from mako.template import Template
 from six.moves import configparser
 from sqlalchemy import and_, false
 
+sys.path.insert(1, os.path.abspath(os.path.join(os.path.dirname(__file__), os.pardir, os.pardir, 'lib')))
+
 import galaxy.config
 import galaxy.model.mapping
 import galaxy.util

scripts/cleanup_datasets/update_dataset_size.py

@@ -10,6 +10,8 @@ import sys
 
 from six.moves import configparser
 
+sys.path.insert(1, os.path.abspath(os.path.join(os.path.dirname(__file__), os.pardir, os.pardir, 'lib')))
+
 import galaxy.app
 
 assert sys.version_info[:2] >= (2, 4)
@@ -24,7 +26,7 @@ running.
 
 
 def main():
-    if len(sys.argv) != 1 or sys.argv[1] == "-h" or sys.argv[1] == "--help":
+    if len(sys.argv) != 2 or sys.argv[1] == "-h" or sys.argv[1] == "--help":
         usage(sys.argv[0])
         sys.exit()
     ini_file = sys.argv.pop(1)