Use link_to_unless helper so it's more readable and path can be figured
out automatically (problem instead of problem_path(problem).
ProblemsController: Use more ruby-like syntax, use .name_was instead of .name (so that
previous name is present in breadcrumbs).
ApplicationController: Use root_path instead of '/'
SolutionsController: Use more ruby-like syntax.
AnalysesController: Use more ruby-like syntax.
OpinionsController: Use more ruby-like syntax.
SummariesController: Use more ruby-like syntax.
Merge branch 'headers-and-breadcrumbs-to-be-consistent'