Added strings for the WelcomeFragment

Added the title string for the WelcomeFragment and added a small welcome
text for the user. Also removed section titles since they are not needed
anymore.
Added a simple layout to ask the user for his location

A simple layout with two buttons, one for letting the app now the
current location through GPS, or a second to manually input the location
information.
Changed the fragment layout for LocatingMethodFragment

Updated the layout used for the LocatingMethodFragment to match the
newly created one.