LONDON (Reuters) – Canadian pop star Justin Bieber was feeling "a little under the weather" on Friday, a day after collapsing on stage, but plans to perform the last of four concerts at London's O2 Arena, a spokesman said. Bieber, 19, suffered from shortness of breath during his performance and, after a 20-minute break during which he was given oxygen by doctors, he completed his set. The "Boyfriend" singer was later taken to hospital. …