COMP: Add option allowing to enable internationalization support.

STATUS
 Internationalization support has been discussed during March 26th 2013
developer hangout.

 We reach consensus: Official support for i18n will be disabled. A CMake
option named Slicer_BUILD_I18N_SUPPORT will be added and the option
won't be actively supported or tested.

 Why? Supporting internationalization properly would require to test
all ITK/VTK/Teem/.. readers and we don't have the funding or resources
to support that effort. If it is something you are interested in, make
sure to drop an email on the developer list. We will be happy to provide
 more information.

DISCUSSION
 http://slicer-devel.65872.n3.nabble.com/Re-Rounding-to-integer-tt4027985.html
 http://slicer-devel.65872.n3.nabble.com/Re-slicer-users-Slicer4-can-t-really-use-it-yet-td4028040.html
 http://slicer-users.65878.n3.nabble.com/Slicer4-DICOM-many-problems-td4025919.html

ISSUES
 3029 - Image spacing not read correctly in Slicer 4.2.2

git-svn-id: http://svn.slicer.org/Slicer4/trunk@21856 3bd1e089-480b-0410-8dfb-8563597acbee
ENH: 1318. Added FOV based on Volumes, resolution based on 2D View mode into reslice functionality

git-svn-id: http://svn.slicer.org/Slicer4/trunk@21857 3bd1e089-480b-0410-8dfb-8563597acbee
COMP: Update build-system to use CMake'ified python

Latest stable version 2.7.3 is now used instead of ancient 2.6.6

Directory layout has been updated:
 - Python-2.7.3   : source
 - python         : build system
 - python-build   : build tree
 - python-install : install tree

Associated external project has been simplified. Removed unneeded
custom configure, make and install steps. Also removed unneeded
patch steps.

Note that the pythonrun.h and pythonrun.c are still patched in order
to prevent crash (related to dll boundaries [1][2]) when building Slicer debug
against a released python.

[1] http://stackoverflow.com/questions/2322095/why-does-this-program-crash-passing-of-stdstring-between-dlls
[2] http://social.msdn.microsoft.com/Forums/en-US/vcgeneral/thread/57e0d522-a42c-4add-963d-c87c6e76f161

Since only library located in the "lib-dynload" folder are not duplicated
in the "site-packages" folder, removed the exclude pattern
from the fixup script and update the candidate pattern to consider the
python extension located in lib/python2.7/lib-dynload folder.