Add icons to tags

- add iconURL to tags model
- retrieve icon when loading tags tableView
Logs and formatting
Update gitignore
Update tags tableview
Button with voxe logo
Update rakefile & TestFlight config (without tokens)
Choose election
Simplify election selection
Only display back button when needed
Fix tags table view row height
Add country flags and spinner
Add HelperViewController

Add a helper view that explains how the app works.
Add tutorial with UIPageViewController

Added tutorial that explains how the app works
Add content for tutorial
Display initial help in propositions view controller
Fix european union flag
Sort countries, tutorial on 1st launch

- Tutorial screen now only loads at first launch
- The countries table view is now sorted by election date
- added lazy instantiation for most instance variables
Merge remote-tracking branch 'upstream/motion' into motion

* upstream/motion:
  Sort countries, tutorial on 1st launch
  Fix european union flag
  Display initial help in propositions view controller
  Add content for tutorial
  Add tutorial with UIPageViewController
  Add HelperViewController
  Add country flags and spinner
  Fix tags table view row height
  Only display back button when needed
  Simplify election selection
  Choose election
  Update rakefile & TestFlight config (without tokens)
  Button with voxe logo
  Update tags tableview
  Update gitignore
  Logs and formatting
  Add icons to tags