PIL removal

remove obsolete PIL/Imaging/Python Image Library,
it was used for image recognition, is now unsupported
and obsolete.

Used eg in people-tracking-demo
PIL add notice to demo using PIL

maybe it got broken, well, it's broken anyway
remove libpng

was used as dependency of PIL (obsoleted too)
mention PIL in requirements.txt for pip

Conflicts:
	external/common/requirements.txt
Dumps stdout from build.sh to a temp file.
Consolidate local variables before functions in build.sh.
Indentation/style fix to build.sh.
Indentation/style fix to cleanbuild.sh.
Make sure stdout file's directory exists.
Merge branch 'master' into verbosity
Merge pull request #190 from scottpurdy/verbosity

Verbosity fixes for build
Revert to using --target option for pip to explicitly install to lib, as
opposed to specifying --prefix, which may result in it being installed in
lib64, which is causing problems in some environments.
Merge pull request #197 from oxtopus/pip-target-option

Revert to using --target option for pip to explicitly install to lib/
Remove --target (again) in favor of specifying --install-lib as an install
option pass-through.
Specify python site-packages in --install-lib option
Merge pull request #199 from oxtopus/pip-install-lib

Remove --target (again) in favor of specifying --install-lib
remove simplejson module, use (standart) json instead

since python 2.6+ simplejson is included in standard python lib as json module.

there are speed disputes: http://stackoverflow.com/a/16131316/78234
but measuring our usecase, .dumps() is used (slightly) more ofthen than .loads(), so json is faster.
Also, bug-fix support is better for json.
update files to import json instead of simplejson
tweepy installed by pip

before was only on Linux, now on both platforms
PS: why is this used? :)

use version=2.1

Conflicts:
	external/common/requirements.txt
psutil installed by pip

version 1.0.1 used

Please test on MacOS, there were some .so files present there...?

Conflicts:
	external/common/requirements.txt