mesos-style by default checks the entire source tree

The default behavior when no args are provided is to check the entire
source tree based on the defined rules in code.  If a list of arguments
is provided they represent file paths to run lint on.  The file paths
that are passed in will be filtered down based on the defined rules
in mesos-style.py which means if it is not a candidate for lint then
it will be ignored. (For now)