add new detecting methods:
- user agent
- connections: UDP, TCP and UDP
- TTL: if there is TTL diff. from major TTL values
- TTL: if there is more than 1 TTL and their values differ by 1

also update the cross validation for new methods.
commit subtasks as well.
add a new parser to parse TCP Timestamp option
add 2 sub-tasks which evaluate the following methods
- clock skew
- boot time attack
mainly forcus on Clock Skew and Boot Time fingerprinting
add new tethering detection method: boot time
- evaluate heuristics by comparing them with User Agent heuristic.
- check some statistics information related to frequency and boot time heuristics
compare result of different heuristics and tune the parameters.
compare
clock skew
ttl distribution
http agent
tcp flavor
ip id
tcp timestamp
tcp window
plot ttl
update ignore list