Enable installer over serial console
This patch contains a couple of small fixes for the installer script.
- checks if installer.sh is being run on a serial console
- if TERM has not been changed (ie: still dialup) it will set TERM to vt100 and ask the user to confirm
- it will then use curseslog with npipe to run dfui
- it will cleanup any running instance of dfuiXX left behind when interrupted (Some of the other check could be removed (not sure)
- will warn the user if they are connected over a slow link (which would slow down the installation considerably (because of debug output).