Fully build plugins/mappings.cfm and plugins/cfapplication.cfm before placing them

There is a potential race condition between reads of these Mura-generated files and writes. This potential is exacerbated when:

* The site is under load.
* The site has an extraordinary number of plugins.

When there are many plugins (we have 24), building these files can take hundreds of milliseconds--enough time for other parts of the app to read those files when they're partially-built.

This modification causes these builders to write to temp files, and then swap out the real files with temp files *after* the temp files are fully-built.