Merge pull request #915 from N0YB/RELENG_2_1

XHTML Compliance
Merge pull request #916 from N0YB/RELENG_2_1

XHTML Compliance
Use https to get updates, it helps #2952
Respect g['tmp_path']
Fix #2952, escape necessary chars to avoid xss injection
Abort installation when pbi_add fails
Add a mechanism by which the serial port can be forced on always regardless of the config setting. (useful for nano+vga setups)
Add a knob to let the user select which console (video or serial) is preferred in cases where there are multiple consoles present. Also provide a way to force this preference.