Merge pull request #2 from jsilvestre/master

Fixed: installation instructions for OSX
handle better the case where device is already registered.
put file list and information in a cache
add date to file descriptors
improve code and add information cache
fix doc
addditional logging for first replication
add helpers for couchmount in dbutils
add comments on replication module + allow to give ids to replication
add missing space
Refactored: password retrieval is done in the CLI client to improve reusability in the GUI client
Improved: error handling and code robustness
Added: first version of the GUI (not fully functional, WIP)
Better error management for 'sync' command