Add button to set current time

When there is a significant difference between the user's browser's time
and the system time, a button appears in the web UI to fix the system
time. This time will then be used to correct both data inside of PCAPs
and any metadata.

We don't actually set the system time to this value. Instead, rayhunter
adjusts any timestamps it handles by an offset. That offset defaults to
zero, and the user adjusts it by hitting the button in the web UI. The
main reason for this is device portability.

I haven't investigated whether it would actually be easy to set the real
system time. It's possible that it works the same way across all
devices.

lib/src/lib.rs

@@ -12,6 +12,7 @@ pub fn init_logging(default_level: log::LevelFilter) {
 }
 
 pub mod analysis;
+pub mod clock;
 pub mod diag;
 pub mod gsmtap;
 pub mod gsmtap_parser;