GNOME dependable installation, structure and style improvements

Split utils in utils.py to a directory
Moved ./gnome-shell_css/ to ./gnome-shell/.css/

scripts/utils/concatenate_files.py

@@ -0,0 +1,12 @@
+def concatenate_files(edit_file, file):
+    """
+    Merge two files
+    :param edit_file: where it will be appended
+    :param file: file you want to append
+    """
+
+    with open(file, 'r') as read_file:
+        file_content = read_file.read()
+
+    with open(edit_file, 'a') as write_file:
+        write_file.write('\n' + file_content)