Revert "[ADD] Compression in xz format of traces"

This reverts commit e5fc1da84cf008a7bb0b628c58e295e6d02d1ede.

We should do that only with the new files
Readme: dailymotion + spotify
Readme: more notes about device' settings
save_traces_purge_phone: just backup
Utils: killTcpdump: added a missing '/'
Utils: tcpdump: added app's name

in the name of the pcap files
launch_tests: Compress all new files
launch_tests: Control more than one IFace
launch_tests: added params to ssh to router
launch_tests: Remove traces and backup
launch_tests: reboot phone at the end