Add upload-sources.bash and README.md to tools/i18n

The upload-sources.bash script can be used to upload the messages.json
file when it gets updated directly to Crowdin.

Also, the blocked users list has been updated.

Change-Id: I8fe8fbc47e7b780198f31711bd1a464d175b4546
diff --git a/tools/i18n/blocked-users.txt b/tools/i18n/blocked-users.txt
index 52ad0a7..0c09010 100644
--- a/tools/i18n/blocked-users.txt
+++ b/tools/i18n/blocked-users.txt
@@ -6,6 +6,7 @@
 viki19822
 jjroot19
 mattiasxxpersson
+JeremyMaloney
 
 # These users joined the project but didn't make any translation, so they
 # shouldn't be credited neither.