Initial commit of an OpenGL Transmission Format (glTF) BIMServer
serializer plugin in conjunction with the following ticket: #105.

This commit provides medium changes to the existing procedure of the
Collada serializer on which the OpenGL Transmission Format depends. This
dependency is in the form of the collada2gltf exporter presented by
Khronos.

"collada2gltf" is required to be on the PATH/available to the
command-line at the operating system level so that the plugins can
function.

The OpenGL Transmission Format family of plugins can and should be
consolidated into 1 single plugin if/when plugin configurations can be
made from the plugin.xml file.
Should close #105; provides OpenGL Transmission Format (glTF) serializer
and associated plugins.

Other provisions: 3d material look-up off a surface style associated
with an IfcProduct, documentation for the Collada serializer, and
documentation for the Collada package in general.
Add pre-packaged binaries for Windows & MacOSX, as requested in #105.

Also provides a copy of the license(s) for that project, updated
documentation, and changes the temporary directory to be beneath a
general "gltf" temporary directory (beneath the BIMServer "tmp"
directory).
Changes mark-down documentation of paths to be italics.
Merge pull request #118 from lirmont/master

Thank you!