Remove changes files for items already in release-0.3.1

changes/bug15582

@@ -1,4 +0,0 @@
-  o Minor bugfixes (compilation):
-    - Avoid compiler warnings in the unit tests for running tor_sscanf()
-      with wide string outputs. Fixes bug 15582; bugfix on 0.2.6.2-alpha.
-

changes/bug17857

@@ -1,6 +0,0 @@
-  o Minor features (defensive programming):
-    - Create a pair of consensus parameters nf_pad_tor2web and
-      nf_pad_single_onion that allow us to disable netflow padding in the
-      consensus for non-anonymous connections, in case the overhead is high.
-      Closes #17857.
-

changes/bug22446

@@ -1,4 +0,0 @@
-  o Minor features (code style, backport from 0.3.1.3-alpha):
-    - Add "Falls through" comments to our codebase, in order to silence
-      GCC 7's -Wimplicit-fallthrough warnings. Patch from Andreas
-      Stieger. Closes ticket 22446.

changes/bug22644

@@ -1,5 +0,0 @@
-  o Minor bugfixes (controller):
-    - Do not crash when receiving a POSTDESCRIPTOR command with an
-      empty body. Fixes part of bug 22644; bugfix on 0.2.0.1-alpha.
-    - Do not crash when receiving a HSPOST command with an empty body.
-      Fixes part of bug 22644; bugfix on 0.2.7.1-alpha.

changes/bug23077

@@ -1,4 +0,0 @@
-  o Minor bugfixes (unit tests):
-    - Fix a channelpadding unit test failure on extremely slow systems
-      by using mocked time instead of actual time. Fixes bug 23077; bugfix on
-      0.3.1.1-alpha. 

changes/bug23105-diagnostic

@@ -1,4 +0,0 @@
-  o Minor features (diagnostic):
-    - Add a stack trace to the bug warnings that can be logged when
-      trying to send an outgoing relay cell with n_chan == 0.
-      Diagnostic attempt for bug 23105.

changes/geoip-september2017

@@ -1,4 +0,0 @@
-  o Minor features:
-    - Update geoip and geoip6 to the September 6 2017 Maxmind GeoLite2
-      Country database.
-