Add 900 for Russia - Short code used by Sberbank.

Sberbank SMS banking solution uses 900 short code.
They have requested this shortcode to be listed has premium to reduce banking fraud.

bug: 28423611

Change-Id: I82dfe012a1e55b2d025c24e50149fa01551a92ed
Signed-off-by: Vasco Brito <vascob@google.com>