Document: Add save().

Document: Add save().

	* src/main/java/org/glom/web/shared/libglom/Translatable.java:
	Added getTranslationsMap() for use while saving.
	* src/main/java/org/glom/web/shared/libglom/layout/LayoutItemField.java:
	Adedd getUseDefaultFormatting() for use while saving.
	* src/main/java/org/glom/web/server/libglom/Document.java: Added save()
	and several private methods that it uses.

	This will be useful while testing via self-hosting.
	It is not complete, but should be complete enough for testing.