made the pack completely portable and wrote relevent bat files to go with it

gitportable/mingw64/share/doc/git-doc/RelNotes/1.7.8.6.adoc

@@ -0,0 +1,22 @@
+Git v1.7.8.6 Release Notes
+==========================
+
+Fixes since v1.7.8.5
+--------------------
+
+ * An error message from 'git bundle' had an unmatched single quote pair in it.
+
+ * 'git diff --histogram' option was not described.
+
+ * Documentation for 'git rev-list' had minor formatting errors.
+
+ * 'git imap-send' carried an unused dead code.
+
+ * The way 'git fetch' implemented its connectivity check over
+   received objects was overly pessimistic, and wasted a lot of
+   cycles.
+
+ * Various minor backports of fixes from the 'master' and the 'maint'
+   branch.
+
+Also contains minor fixes and documentation updates.