Some refactoring proposals

[Steve Markgraf]

Hi,

I have some pending changes in steve-m/pending and steve-m/l1reset as 
well. The first branch is based on current master, and re-enables the 
gta0x images, the l1reset branch is based on sylvain/pending and adds a 
l1ctl_tx_reset_req() on startup of the layer2 applications.

Thus, you don't have to start the layer2 application before powering the 
phone anymore, and you can switch between different layer2 apps without 
rebooting the phone. The first case still works, since the layer1 reset 
ack is received anyway.

Regards,
Steve