Point other profiles to new data dir after migration (+ code reorg)

Look for other profiles, from both apps (Firefox and Standalone), that
point to the data directory being migrated and update prefs.js in those
profiles to point to the new location.

Also reorganize code into Zotero.Profile and Zotero.DataDirectory
namespaces

components/zotero-service.js

@@ -33,6 +33,7 @@ const Ci = Components.interfaces;
 /** XPCOM files to be loaded for all modes **/
 const xpcomFilesAll = [
 	'zotero',
+	'dataDirectory',
 	'date',
 	'debug',
 	'error',
@@ -41,6 +42,7 @@ const xpcomFilesAll = [
 	'mimeTypeHandler',
 	'openurl',
 	'ipc',
+	'profile',
 	'progressWindow',
 	'translation/translate',
 	'translation/translate_firefox',