Also renamed header.wxs to template.wxs in setup.py, as we're going to
insert into the middle of its content, not use it as a simple
concatenated header.
* We'll be generating EDMarketConnector.wxs, so remove it from git and
add to .gitignore
* Initial work on using `lxml` to parse in wix/components.wxs, generated
by heat.exe, to pick out what we need, modify it, and eventually
stitch into a generated EDMarketConnector.wxs
