modular: asteval python module installed by pip

ver 0.9
dateutil installed by pip

modulename is python-dateutil
version 2.1 is used

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

six (1.3) is a requirement for dateutil

Conflicts:
	external/common/requirements.txt
mock python module installed by pip

version 1.0.1 is used
validictory python module installed by pip

0.9.1 version used

Conflicts:
	external/common/requirements.txt
unittest2 python module installed by pip

not needed for python2.7+
pylint installed by pip

unittest2, logilab-common, logilab-astng are dependencies
version 0.28.0 used
logilab, ordereddict installed by pip

logilab-common, logilab-astng are dependencies of pylint
ordereddict is backported from python 2.7 (=not needed for python2.7+)

PS: these two commits are together because my mistake, no magic here :P
remove link to unused folder
Removing sub-dependencies from requirements.txt
Alphabetically-ordered requirements.txt
Merge pull request #148 from oxtopus/modular-python-common

Modular python common (revised)
Merge with master