Save instance state for TranslationFragment
More refactoring
More refactoring.
+ Decoupled TranslationFragment from HistoryHelper
+ Unsupported uiLanguage will fallback to "en".
+ Added Internet reachability test

TODO:
* fix bug in save/restore of TranslationFragment
* Delete/clear history
* Add undo action in TranslationFragment
* Localize all UI strings!
* Provide better UX on tablets
Minor change (fix default target languag
)

TODO:
* fix bug in save/restore of TranslationFragment
* Delete/clear history
* Add undo action in TranslationFragment
* Localize all UI strings!
* Provide better UX on tablets