Is it possible to run Xcode 7 UI Tests from command line?

Yes, with something like this ...

xcodebuild test -scheme YourAppScheme -destination platform=iOS\ Simulator,OS=9.0,name=iPhone\ 6

Replace your project's scheme name in for 'YourAppScheme'

Used to be you had to export/share the scheme (go to manage schemes in Xcode) to get this to work. Not sure if that is still the case. Just a warning.

You can play with the destination settings to pick different devices, etc.

Cheers.