Exclude .git-blame-ignore-revs to fix CI

.git-blame-ignore-revs is added so that  we can ignore revisions in .git-blame,  mostly code reformatting; but CI check that all files are explicitly included (or excluded) from manifest; so we need to list this one explicitly for travis to succeed.

MANIFEST.in

@@ -24,6 +24,8 b' graft docs'
 exclude docs/\#*
 exclude docs/man/*.1.gz
 
+exclude .git-blame-ignore-revs
+
 # Examples
 graft examples