* Growth falls short of expectations in second quarter* Finance minister sees threat to 2014 4 pct target* Lira at weakest since late March* Slower growth will heighten pressure for rate cuts(Adds Finance Minister Mehmet Simsek)By Ayla Jean Yackley and Behiye Selin TanerISTANBUL, Sept 10 (Reuters) - Turkey&aposs economy grew less than expected in the second quarter, helping send the lira to its lo