report the actual url as request_url

Reporting the hash turns (for me) out to be error prone as I do not get the actual host.
Add Flowdock notification adapter
Update *from* email to display a valid Flowdock avatar
Flowdock doesn't validate or have some sort of confirmation for email addresses. As long as you know Flow API token you're free to post with any email.
Merge comment with problem during the merge of some problem

see #477
extract Fingerprint#generate from ErrorReport
move the validations for error_class and environment from Err to Problem

Problems are the models rendered in the UI now, not Errs. Errs are functioning as a glorified hash table. It makes more sense to validate problems.

Also, this paves the way for the next commit, so that no functionality is lost in the subsequent refactor.
Errs are like a hash table whose values are arrays of notices and whose keys are a composite of error_class + component + action + environment + backtrace[0..3].

These fields no longer need to be cached separately on Err because they are now cached on Problem.

This commit combines all those values into one simple key: fingerprint. This should:

 - Make err lookups faster
 - Make it easier to reason about, test, and replace the fingerprint algorithm
 - Make the relationship between Problems, Errs, and Notices clearer
Merge pull request #253 from concordia-publishing-house/extract-fingerprint

Refactor: extract Fingerprint#generate from ErrorReport
Merge pull request #508 from shingara/features/merge_comment_too

Merge comment with problem during the merge of some problem
Upgrade to Devise 2.2.x version

The Devise version was old so we upgrade to the latest version
Merge branch 'features/update_devise'
udpate changelog [ci skip]
update hipchat gem
update some gem and dev gem [ci skip]
Extract I18n key from views/layouts/application.html.haml
Extract translation key on navigation and session bar
Merge pull request #504 from nfedyashev/flowdock_notification_adapter

Conflicts:
	Gemfile.lock
Tell to run bundle in the Heroku deploy instructions

Without running first `bundle` I get the following error when running `heroku config:add SECRET_TOKEN="$(bundle exec rake secret)"`

/Users/florent2/.rbenv/versions/2.0.0-p0/lib/ruby/gems/2.0.0/gems/bundler-1.3.5/lib/bundler/spec_set.rb:92:in `block in materialize': Could not find i18n-0.6.1 in any of the sources (Bundler::GemNotFound)
Merge pull request #513 from Florent2/patch-1

Tell to run `bundle` in the Heroku deploy instructions
[WIP] Start refactoring the problems_controller.

1) Limit some before_filter using the expose system
2) Extract some view test in view spec instead of controller spec