Styled new history tab layout.

There are few `FIXME`, please review them.
Fixed according to first review.
Fixed another style error.
Added black and white avatars.

The problem with black and white avatars is that in a single project there could be thousand of people with a name starting with **M**, so them become just useless. In this case the colored avatars become very very very useful because are the only way (without internet) to have different avatars for each user.
Added string `requires internet`
Implemented @SAPlayer version of colored avatars.
Fixed dropdown-menu style of `reset-index` btn.
improved error handling
fix a bug
fix possibly unhandled call in gutters
progress dialog for long running operations
clear lines with every progress
Changelog is a mess ...
Various improvements of history tab.
Removed md5 dependency, draft for GitHub avatars.
license...
Issue #361
git-reset changed to git-refresh
Issue #363
rename folders to lowercase