tiny changes to CSS and logic, also closes #9

* Additonal telemtry from habitat is displayed only in 'landscape mode'
* added a WARNING to the 'chase car' page that position will be made public
* move the position of 'no vehicle' message
* 'recieved by' is now hidden, if there are no recievers (e.g. chase cars)
* ChaseCar lib now sends values that are null as 0
updated position logic