Uploaded question_013.  (16 minutes to implement basic functionality; 17 minutes to add options and defaults for case insensitive searches and for ignoring hidden directories and files)

# Write code to search and return all those file names present in a given directory
# (for e.g. C:\>) where the string "Amazon" is present. All the files will be located
# at different folder levels. Also discuss your approach, time and space complexities
# for your solution.
#
# ref: http://www.careercup.com/page?pid=software-engineer-in-test-interview-questions