Track now properly traverses folder structure
Specs for track
Track makes entries in .manifest

When a user tracks a file or directory that is in
a nested folder, Homesick creates a .manifest in the
user's castle (if there isn't one already) and adds
an entry listing the file or directory's parent
directory (if it isn't already listed).
Handling edge cases

Covers only edge cases related to tracking, not yet
handling linking or updating. Getting a bit hairy,
must be refactored.
refactor, cleanup and tweak
Merge remote-tracking branch 'edubkendo/nested_dirs' into feature/merge_directory
replace .manifest to .homesick_subdir