Don't throw error when repo can't be find

When visiting page of repo that doesn't exist, we should not throw an
error. It still does not work as expected, redirecting to
/undefined/undefined, which should be addressed as well, but at least we
don't throw errors now.
Merge branch 'master' of github.com:travis-ci/travis-web
Fallback to login if name is not given for a user
Update README.md
Few more changes in README
Sometimes empty value is passed to lines, abort in such cases