By Dominic Evans BEIRUT (Reuters) - Syrian President Bashar al-Assad's forces launched a major offensive on Saturday against rebels in Homs, a centre of the two-year-old uprising, in their latest drive to secure an axis connecting Damascus to the Mediterranean. Activists said jets and mortars had pounded rebel-held areas of the city that have been under siege by Assad's troops for a year, and soldiers fought battles with rebel fighters in several districts. "Government forces are trying to storm (Homs) from all fronts," said an activist using the name Abu Mohammad. ...