Include Stats information in response

This is for debugging and analyzing performance later.
No need for verbose

The log should contain everything currently available.
exported first
Begin work on other cpdf commands
Save a variable
Only start server if specified

This creates a -server option, without which the program will operate in
an as-yet-unimplemented standalone mode where the files to combine can
be specified on the command line.
Move all HTTP stuff to the server package

main() is getting bloated.  There's no reason it needs to know how to
start a server.
remove previously finished TODO