(Reuters) - A technical glitch delayed the start of trading on Friday on the UK blue chip FTSE 100 and midcap stock indexes for almost two hours in what was the longest outage at one of the world's top bourses in eight years.The London Stock Exchange suffered a "technical software issue", which postponed the opening of trading until 0840 GMT, a spokeswoman said in an email. The markets normally open at 0700 GMT.In a statement on its website, it said it was still investigating the issue.The..