Fix translations and extract missing translations

This fixes a couple issues that were preventing translation changing to work correctly (see commit message for details). It also extracts out many missing strings that needed to be translated. This should be just about everything that we can potentially extract for translation. There are some things that cannot be extracted without a lot of work. These remaining items are:
* Base map names and attributions
* Some third-party directives such as the file uploader and date picker
* Any messages generated via the GTFS Validator and Scala (error messages, etc.)