Stylish Formatter: output all file names (#1557)
Stylish Formatter: output all file names (#1557)

Currently the stylish formatter *only* prints the first fileName, and
then a list of lint errors from all files without specifying to which
file they belong.
After this fix, each time a new file is reached, a new line will be
added, and then the name of the file, so each group of lint failures
will be group with their fileName.

berickson1/tslint,andy-hanson/tslint,YuichiNukiyama/tslint,berickson1/tslint,YuichiNukiyama/tslint,palantir/tslint,YuichiNukiyama/tslint,RyanCavanaugh/tslint,IllusionMH/tslint,IllusionMH/tslint,nchen63/tslint,IllusionMH/tslint,JoshuaKGoldberg/tslint,JoshuaKGoldberg/tslint,RyanCavanaugh/tslint,mprobst/tslint,JoshuaKGoldberg/tslint,nchen63/tslint,RyanCavanaugh/tslint,andy-ms/tslint,mprobst/tslint,andy-hanson/tslint,nchen63/tslint,andy-ms/tslint,andy-hanson/tslint,palantir/tslint,mprobst/tslint,berickson1/tslint,palantir/tslint,andy-ms/tslint