issueLink -> issue_link and make capitalisation of stauses consistent in en.json

The general convention in this file uses snake_case, and this is also what bug.js is looking for already anywways.
The strings for postponed and closed statuses were lowercase, while all other statuses are in title case (like on jira as well)

i18n/en.json

@@ -396,7 +396,7 @@
         "more": "And $1 more.",
         "private": "**Private Issue**",
         "total": "$1 {{PLURAL:$2|issue|issues}} fixed",
-        "issueLink": {
+        "issue_link": {
             "duplicates": "duplicates $1",
             "relates_to": "relates to $1",
             "blocks": "blocks $1",
@@ -412,8 +412,8 @@
             "in_progress": "In Progress",
             "resolved": "Resolved",
             "reopned": "Reopened",
-            "closed": "closed",
-            "postponed": "postponed",
+            "closed": "Closed",
+            "postponed": "Postponed",
             "fixed": "Fixed",
             "wont_fix": "Won't Fix",
             "duplicate": "Duplicate",