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)

unicornscan compatible output for tcp scans

forgot to add out-unicornscan.c

use '-oU' or '--output-format unicornscan'

Only supported for TCP SYN scanning. Other scans
will fall back to grep style output since unicornscan
has no support for non-TCP scanning.

use '-oU' or '--output-format unicornscan'

Only supported for TCP SYN scanning. Other scans
will fall back to grep style output since unicornscan
has no support for non-TCP scanning.

fixed bug where --echo didn't set ping = true for --ping scans

changed --echo to exit(0) instead of exit(1)