Files are not getting added to the index after copying files

On windows machines the last modified date is not updated when you copy a file.
For copied files the creation date has to be used. This does not cover renaming
files.

Solves issue #60
Files are not getting added to the index after copying files

On windows machines the last modified date is not updated when you copy a file.
For copied files the creation date has to be used. This does not cover renaming
files. Using java.nio library to get file creation date. This requires java 7

Solves issue #60