checkloc - Add script to validate localization data

This new python script checks everything the old perl script did, AND MORE! :)
See the file for details on tests run.
Rather than replacing characters in localization files, we simply detect and report errors.
The builder can then fix files in the manner they wish.
This is less error prone and keeps builders aware of issues.

Also, using a python script rather than a perl script
keeps the languages consistent for devs who work on both
the Perspectives client and server (they only need to install one language).

Running the localization tests at build time lets us validate data *before*
it gets into the extension. It also means the tests do not rely on
any browser API or javascript capabilities.

This should be much more robust for the future and allow us to quickly
iterate on and validate localization updates with confidence.

Many thanks to the lxml team for writing a great library.
Makefile - Remove old localization perl script; add python script

Run localization tests as part of the build
checkdtds - delete file

No longer needed; the new python localization tests
cover everything this script did, and more.
README - Change requirements to python and lxml
Localization - Convert Finnish file to proper UTF-8 encoding