Remove changes files for issues resolved in 0.3.0.7.

changes/bug21943

@@ -1,6 +0,0 @@
-  o Minor bugfixes (Linux seccomp2 sandbox):
-    - The getpid() system call is now permitted under the Linux seccomp2
-      sandbox, to avoid crashing with versions of OpenSSL (and other
-      libraries) that attempt to learn the process's PID by using the
-      syscall rather than the VDSO code. Fixes bug 21943; bugfix on
-      0.2.5.1-alpha.

changes/geoip-may2017

@@ -1,4 +0,0 @@
-  o Minor features:
-    - Update geoip and geoip6 to the May 2 2017 Maxmind GeoLite2
-      Country database.
-

changes/prop275-minimal

@@ -1,9 +0,0 @@
-  o Minor features (future-proofing):
-
-    - Tor no longer refuses to download microdescriptors or descriptors if
-      they are listed as "published in the future".  This change will
-      eventually allow us to stop listing meaningful "published" dates
-      in microdescriptor consensuses, and thereby allow us to reduce the
-      resources required to download consensus diffs by over 50%.
-      Implements part of ticket 21642; implements part of proposal 275.
-