Installer is now able to detect the latest available release (latest tag)....

Installer is now able to detect the latest available release (latest tag). Added new options to the installer: --update to update the SW; -b branch to use a specific branch.

Change-Id: Ifbc834f8886d9c7c3f4f47a49a6b11a1982241c2
Signed-off-by: garciadeblas <gerardo.garciadeblas@telefonica.com>