Ensure Gravatar ing alt tags aren't empty

Fixes Bugz 2626
A more generous check of alt tag "emptiness"
Support user id lookup (not just comment lookup)

Fixes Bugz 2626
v1.2.2: Nav Menu span tags
Disable the rel=prev and rel=next links in <head> section
v1.2.1 readme
Merge pull request #1 from OM4/develop

Release v1.2.2