Only running coveralls on one linux build job.

There's no point running it twice, and the OSX environment seems to have
changed, so installing coveralls isn't working anymore. I've updated the
build config to only install and run coveralls on Linux Py2.7 clang,
which still seems to be working.

I also noticed that the echo commands were not showing the names the
scripts properly within Travis, so I hand-jammed the names into the
scripts so I can better see what scripts are actually being executed.