Remove changes files already merged into release-0.2.2

changes/bug2230_part1

@@ -1,7 +0,0 @@
-  o Minor bugfixes
-    - When loading the microdesc journal, remember its current size.
-      In 0.2.2, this helps prevent the microdesc journal from growing
-      without limit on authorities (who are the only ones to use it in
-      0.2.2).  Fixes a part of bug 2230; bugfix on 0.2.2.6-alpha.
-      Fix posted by "cypherpunks."
-      

changes/bug2230_part2

@@ -1,5 +0,0 @@
-  o Minor bugfixes
-    - The microdesc journal is supposed to get rebuilt only if it is
-      at least _half_ the length of the store, not _twice_ the length
-      of the store.   Bugfix on 0.2.2.6-alpha; fixes part of bug 2230.
-

changes/bug2230_part4

@@ -1,6 +0,0 @@
-  o Minor bugfixes:
-    - Authorities now clean their microdesc cache periodically and when
-      reading from disk initially, not only when adding new descriptors.
-      This prevents a bug where we could lose microdescriptors.  Bugfix
-      on 0.2.2.6-alpha.
-