Bug 903947 - [Messages] The last recipient is copied everytime when selecting recipeint for removing r=julienw

https://bugzilla.mozilla.org/show_bug.cgi?id=903947

- Clicks on accepted recipients...
    - Should close the keyboard, if it's a known contact recipient
    - while manually entering a recipient:
        - Two rendered recipients
        - A placeholder for the cursor
    -  with only accepted recipients:
        - no changes, no assimilated recipients
    - with no placeholder at end of list:
        - no changes, no assimilated recipients

This patch also fixes https://bugzilla.mozilla.org/show_bug.cgi?id=903943

Signed-off-by: Rick Waldron <waldron.rick@gmail.com>