Resubmit of spy_file chisel.  See github sysdig issue #230 for previous conversation.

Example usage:

[root@web01 ~]# sysdig -c spy_file "rw /var/log/messages"
22:10:30.827285182 rs:main(25251) W 72B /var/log/messages
Aug 22 22:10:30 web01 mod_wsgi[23998]: XXXXXXXXXX RPC: get_map(raw = 1)

22:10:31.179507012 rs:main(25251) W 72B /var/log/messages
Aug 22 22:10:31 web01 mod_wsgi[26529]: XXXXXXXXXX RPC: get_map(raw = 1)
Merge pull request #232 from ryanchapman/master

Resubmit of spy_file chisel.  See github sysdig issue #230 for previous ...
cleanups
improve the heuristic to detect when an entry in /proc is a kernel thread.
wrong file name
decrese scap minimum read size to 2KB
improved the scap buffer timeout logic
more improvements in the scap buffer timeout logic
delete directory after tests
Update sysdig.cpp

fixed typo
Update sysdig.8

fixed typo
Update sysdig.md

fixed typo
Merge pull request #236 from lukaspustina/master

Fixed typo in documentation
make sure that switch events don't pollute the filtering system state
wrong zlib define
merge master