Adding exclusion feature

Adding use of exclude_filter to add a list of directories or files to exclude. Thoses files or directories should be in the path to watch.
Adding list of files and directories to not watch, exclusion feature added in watcher.py
Adding list of directories or file to not watch : exclusion feature
Merge pull request #10 from Brunus-V/master

Adding an exclusion feature to exclude paths and files from being watched