Add timestamp field to JSON output.

Various fixes involving port handling and resumption

Previoulsy port ranges where echoed without the type which resulted in an error when trying to load the configuration file if using non TCP ports. This patch allows for full generation of prefixed ports to overcome this problem.

The number of retries is needed in the pause.conf file to ensure the seed holds with the scan values. This patch ensures the value is echoed out always.

Until now if the user pressed Control+C whilst the program was cleaning up (for example waiting for pending packets) the program would die inmediately. This patch renames  the globals control_c_pressed and control_c_pressed_again to much clearer tx_done and rx_done. It also adds propper handling of control_c count handling in the handler itself as a result the wait will now only be cancelled when pressing control+c a second time during the program life instead of on the first control+c if the user pressed it when we are already doing the scan.

We introduce the --nostatus parameter which allows disabling the printing of status updates.
Aside, we allow for reenabling them using the --status parameter

Fix build failure with GCC 5

Patch applied in Debian to solve FTBFS with the GCC's new
version. The original bug report is available here:
- https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=777997

Fix FTBFS on most Debian architectures

Fixes Debian#773786 and enables support on non-ARM,
Non-x86, and kFreeBSD architectures.

JSON names/keys are now quoted to be strings in output

JSON names(keys) output are now strings (double-quoted as per http://tools.ietf.org/html/rfc7158#page-6)