Display analysis results per file

It shows results in more human way but the error
page is still far far from perfect.

Also refactored bits of the codebase:

* Replaced Analyzer::Status and Analyzer::Result with
  Analyzer::AnalyzedFile.

* Instead of using a regular array, the analysed files are now
  wrapped in the AnalyzedFileSet object.
Merge pull request #54 from X8/display_errors

Display analysis results per file