Update to 2015 version

[gilbertwat]

• prepare it for translations
• update to 2015 formulas

Contact Point : @vincentlaucy @gilbertwat

[debuggingfuture]

will migrate to this repo
https://github.com/code4hk/budget-calculator

Cedric will help on translations at
http://vincentlcy.oneskyapp.com/collaboration/translate/project/project/22255/language/45#/