show avatars in log (gravatar)

[strayge]

Show avatar for author in commit log.

• fetch avatars from Gravatar with hashed author email
• can be disabled via settings
• fallback to author initial letter (during load or load errors, ex.: no internet access)

Before

Enabled avatars

Disabled avatars

Fallback to initial letter

Fallback to initial letter with white theme

[phil294]

Great, thanks! Will release later today.