WIP: Performance testing of asset metadata in course import/export

First iteration of code which tests performance of asset metadata during course import/export. Uses external code_block_timer module. Also, add script which validates XML file against an XSD file.
> I wasn't sure of the approval process for adding a new module to edx.

@doctoryes : I'm not sure about an official process, but I recently moved a project to edx organization that was started as a personal repo.  devops has the ability to edit projects owned by edx, so you just need to enter a ticket by emailing them.  They will temporarily add you as an admin to edx organization.  Then in your repo's settings on Github, you can do a "transfer ownership" to edX organization.  It transfers everything, including PR's and commit history... At least that's how the process worked for me.

You should slap a license and copyright headers on it before transferring.  fwiw, I used the Apache 2 license for the project I recently moved there (after consulting with Ned from OpenEdX).