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...

config/locales/activerecord.he.yml

@@ -0,0 +1,12 @@
+he:
+  activerecord:
+    errors:
+      models:
+        account:
+          attributes:
+            username:
+              invalid: ספרות, אותיות לטיניות וקו תחתי בלבד
+        status:
+          attributes:
+            reblog:
+              taken: של החצרוץ כבר קיים