DRILL-4380: Fix performance regression: in creation of FileSelection in ParquetFormatPlugin to not set files if metadata cache is available. This closes #369
This change is slightly modified from the version in the master branch,
as the 1.5 release branch did not include the Guava version update. The
change simply uses the old constructor pattern for creating StopWatch
objects.
Also backported the change of the FileSelection object constructor to
public access. As stated in the DRILL-4380 discussion the usage patterns
of creating FileSelections and a clarification of the API will be covered
by DRILL-4381.
