PCT-1085
PCT-1085 Fix empty fingerprint

This also fixs PCT-1006
PCT-1085 regex for use and some comments
PCT-1085 New test for empty queries
PCT-1085 Fixed the detection of a use command
PCT-1185 Gofmt and renamed var
PCT-1085 useRe moved outside the func
Merge pull request #3 from percona/PCT-1085

PCT-1085