add SmartInfo

This feature provides relevant advanced information during a call.

The public API has:
- start() and stop()
- setRefreshTime(<timeMS>)
- changed() -- signal
- getters

[Guillaume Roguez <guillaume.roguez@savoirfairelinux.com>: edit for daemon API sync]
[Guillaume Roguez <guillaume.roguez@savoirfairelinux.com>: better code writting]

Change-Id: I5eb464cdfacfbf2eda318c6945c128f8b64860fc
Reviewed-by: Guillaume Roguez <guillaume.roguez@savoirfairelinux.com>