Add Hebrew interface translation. (#2573)

* follow the instructions for registering the language as stated on the Tootsuite's docs.

* Added translation strings from latest master

Adding ‏ characters to many strings that are misdirected in the interface.

A tiny grammar fix

Updates of Hebrew strings to v1.3.1

Hebrew translation of the mailer templates.

Fix strings and a missing comma.

Just discovered two string keys were updated. this should lay Travis' mind to rest at last.

Remove mentions before counting characters to decide RTL ratio

Fixes for PR #2573

updated strings for latest master

Undo RTL counting, moved out to another branch for future consideration...