Install kernel headers on Travis CI to build the driver

Signed-off-by: Christian Babeux <christian.babeux@0x80.ca>
Add Debug and Release build support on Travis CI

Signed-off-by: Christian Babeux <christian.babeux@0x80.ca>
Merge pull request #110 from cbab/travis-ci

Travis CI improvements
fileslower tool for investigating latency outliers
Fixed compilation of driver for sh.
Made building of libscap examples optional.
Language name is Lua, not LUA.

http://www.lua.org/about.html#name
Merge pull request #116 from annulen/fix_sh

Fixed compilation of driver for sh.
Merge pull request #117 from annulen/disable_examples

Made building of libscap examples optional.
Merge pull request #118 from annulen/lua

Language name is Lua, not LUA.
Use relative path to includes to examples work even when included by the agent cmake file
fixed a number rounding issue in chisels' format_time_interval()
Merge pull request #113 from brendangregg/master

fileslower tool for investigating latency outliers
use format_time_interval() to render the times in the fileslower chisel
revert the formatting change in the fileslower chisel. ms works better to visually identify outliers.
apply the display filter *after* giving a chance to the formatter to render the event
only include linux includes on linux

let's be honest: there are so many different OS out there. so let's not
test against a blacklist of OSes but just include linux headers when
__linux__ is defined.
add suport for arch_prctl in the driver (just detection, no decoding)
add suport for shmat, sigreturn and fallocate in the driver (just detection, no decoding)
add suport for shmat, sigreturn and fallocate in the driver (just detection, no decoding)