Bug 1053709 - Make SMS messages content UI RTL-friendly

- Mirror the incoming/outgoing message bubble layout
- Use  unicode-bidi: -moz-plaintext to display the content properly
It's good question for the thread list, it sounds reasonable that the list content direct should depends on the text instead of default language, but Jenny and I thought the it looks weird if we only set the content to different direction. I will raise this to bugzilla for Ahmed and Stephenie