A Study to Evaluate the Safety and Immunogenicity of GSK Biologicals' Candidate Vaccines RTS,S/AS02D (0.5 mL Dose) and RTS,S/AS02A (0.25 mL Dose) Administered IM According to a 0, 1, 2 Month Vaccination Schedule in Children Aged 3 to 5 Years Living in a Malaria-endemic Region of Mozambique.