add project avatar image to Project index and show pages

* added :avatar_url field to Project table for efficiency
* project avatar image replaces octocat on Project show page
* project avatar url updates in Project#update_repository_info
merge latest upstream master
Blacklist several projects
Update pl.yml
Merge pull request #187 from SirCmpwn/master

Blacklist projects I have authority under
Merge pull request #188 from ireun/patch-2

Update pl.yml
Polished up Polish translation :)
Merge pull request #189 from ireun/patch-3

Polished up Polish translation :)
Merge pull request #140 from bits4commits/project-avatar

add project avatar image to Project index and show pages
fixed collobarators
update info for 100 projects per iteration
hint regarding min tip size
Merge branch 'master' of github.com:tip4commit/tip4commit
merge latest upstream master