Updates .gitignore

To ignore swap files from getting into repository
currently the implemented ignore is *.swp
however vim adds more swap files if these files exists,
so improving this with *.sw?

Change-Id: Ic3e09f8cf0be35c98d89d862d40121a09c7b2498
Closes-Bug: #1255876

.gitignore

@@ -7,7 +7,7 @@ subunit.log
 cover
 *.pyc
 .idea
-*.swp
+*.sw?
 *~
 build
 dist