upgrade the vagrant VM to gcc 4.8.2

[pberto]

This is according to Maya 2016 and Houdini 15 sys req.

Ref:

• Maya: http://around-the-corner.typepad.com/adn/2015/04/maya-compiler-versions-update.html
• Houdini: http://www.sidefx.com/index.php?option=com_content&task=view&id=3151&Itemid=424
• http://www.vfxplatform.com

No need to switch to centos, ubuntu/debian is fine for now.

[panta]

Done.

The multiverse-build-machine and alembic-builder have both been updated to use ubuntu trusty and gcc 4.8.4 (that is the 4.8 available in ubuntu out of the box, but the changes should be the same as per 4.8.2) and need these fixes to build correctly.
See/use the ubuntu-trusty64-gcc48-multiverse-1.5.8 of the multiverse-build-machine.

Going to add support also for centos (and exactly gcc 4.8.2 there).