Allow excluding paths from S3 sync
Allow excluding patterns from LocalFile.find
Use Dir.entries to find files in Syncer::Cloud::LocalFile.find_md5 and allow regexes to exclude files.
Workaround for issue with File.file? always returning false for symlinks
Undo workaround from previous commit
add #exclude to all syncers
only MD5 files that are valid and not excluded
Merge branch 'cloud_syncer_excludes'

Adds ability to exclude files from Syncers.

closes #489