use json.h from the include path instead of hardcoding third-party

this allows using the proper header files while linking to the system
jsoncpp when using -DUSE_BUNDLED_JSONCPP=NO
When compiling with an external jsoncpp, the embedded version should not be used whatsoever.
Merge pull request #175 from evgeni/no-third-party-jsoncpp

use json.h from the include path instead of hardcoding third-party
ga tracking added
ga tracking added pixel image
Support EL7
indentation
Use system stock Lua if LuaJIT is not available.
Fix for kernels >=2.6.34 - get_mm_counter() not exported
Merge pull request #178 from leszekgrzegorek/master

Fix for kernels >=2.6.34 - get_mm_counter() not exported
Merge pull request #176 from debfx/stocklua

Use system stock Lua if LuaJIT is not available.
/proc should not be parsed for offline scap sessions
VERBOSE cmake output
proc.apid and proc.aname filter fields
Fixed help text (default event line format)
Default output format help consistent with wiki
Support splice
Avoid use of deprecated table.getn.

table.getn is deprecated function in Lua 5.1 left for compatibility
with 5.0, use # operator instead.

Also, fixed typo.
Merge pull request #182 from annulen/getn

Avoid use of deprecated table.getn.
Merge pull request #180 from annulen/splice

Support splice