Bump version 0.5.4

Change-Id: I2b85f54ccbdd1971b33aa8e4ae8c2bc6b9c91252
Reviewed-on: http://review.couchbase.org/41094
Reviewed-by: Sergey Avseyev <sergey.avseyev@gmail.com>
Tested-by: Sergey Avseyev <sergey.avseyev@gmail.com>