v1.8.0

Now users can choose Gravatar or local avatar image to display on home page. And I also made the size parameter of Gravatar changable.

Please change the settings from:

[params]

  [params.gravatar]
    email = "hugo@example.com"

to:

[params]

  [params.avatar]
    use = "local"  # "local" or "gravatar"

  [params.gravatar]
    email = "hugo@example.com"
    size = 240

  [params.avatar.local]
    path = "example.png"  # please put the image in the static directory

Resolves #5.