Remove BOM mark from litres plugin and also handle BOM mark when downloading plugins

src/calibre/gui2/store/loader.py

@@ -37,7 +37,7 @@ def download_updates(ver_map={}, server='https://code.calibre-ebook.com'):
         name = name.decode('utf-8')
         d = decompressobj()
         src = d.decompress(raw)
-        src = src.decode('utf-8')
+        src = src.decode('utf-8').lstrip(u'\ufeff')
         # Python complains if there is a coding declaration in a unicode string
         src = re.sub(r'^#.*coding\s*[:=]\s*([-\w.]+)', '#', src, flags=re.MULTILINE)
         # Translate newlines to \n

src/calibre/gui2/store/stores/litres_plugin.py

@@ -1,4 +1,4 @@
-# -*- coding: utf-8 -*-
+# -*- coding: utf-8 -*-
 
 from __future__ import (unicode_literals, division, absolute_import, print_function)
 store_version = 1 # Needed for dynamic plugin loading