Add sections to changes files; please lintchanges

changes/bug11454

@@ -1,4 +1,4 @@
-  o Minor bugfixes:
+  o Minor bugfixes (certificate handling):
     - Remove any old authority certificates that have been superseded
       for at least two days.  Previously, we would keep superseded
       certificates until they expired, if they were published close

changes/bug11457

@@ -1,4 +1,4 @@
-  o Minor bugfixes:
+  o Minor bugfixes (certificate handling):
     - If an authority operator accidentally makes a signing certificate with
       a future publication time, do not discard its real signing
       certificates. Fixes bug 11457; bugfix on 0.2.0.3-alpha.

changes/bug14980

@@ -1,4 +1,4 @@
-  o Minor bugfixes:
+  o Minor bugfixes (testing):
     - Fix endianness issues in unit test for resolve_my_address() to
-      have it pass on big endian systems. Resolves issue 14980; bugfix on
+      have it pass on big endian systems. Fixes bug 14980; bugfix on
       Tor 0.2.6.3-alpha.