Update strings.xml

Almost done
Update strings.xml

\' were put back, where missing.
Merge pull request #14 from jeromemorignot/Translation-Review-French-Android

Translation review french android
Merge pull request #15 from muckachina/Updating-French-for-Android

Updating french for android
Merge pull request #47 from muckachina/master

Here the French translation for FrostWire Android