Rename Marconi to Zaqar

This patch renames every package, file, match of Marconi in the codebase
to Zaqar *except* for the .gitreview file, which will have to be updated
*after* I8e587af588d9be0b5ebbab4b0f729b106a2ae537 lands.

Implements blueprint: project-rename

Change-Id: I63cf2c680cead4641f3e430af379452058bce5b3