Introducing the multi-language support #11

The application is now supporting a multilanguage version, including English, Français and Deutsch (and increasing).
It uses by default the application device settings but it can be change on the application.
If the language is unknown, English will be used.

The language settings are loaded meanwhile the splashscreen is displayed (see following commit).
Setting the minimum Android version to API 15 (4.0.3 Ice Cream Sandwich).
[FIX] Fixing some android attributes no available on API 15.
[ADD] Introducing the splash screen activity.

This activity will be used to cover the loading process for saved data, preferences and initializing processes.
Merging the changes with the main repository
Merge pull request #30 from Akhilian/master

Multi-language support and Introducing the splash screen