ec2 api should check 'max_count'&'min_count' para

in ec2 api,run_instance method have not check para
about 'max_count' and 'min_count'

Change-Id: I852dac71e56c658a54b127053cba155e1a260a73
Closes-Bug: #1267382
Merge "ec2 api should check 'max_count'&'min_count' para"