Add 6.4.1 and 6.4.2 CHANGELOG

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Conflicts:
	CHANGELOG

CHANGELOG

+v6.4.2
+  - Fixed wrong behaviour of script/upgrade.rb
+
+v6.4.1 
+  - Fixed bug with repository rename
+  - Fixed bug with project transfer
+
 v 6.4.0
   - Added sorting to project issues page (Jason Blanchard)
   - Assembla integration (Carlos Paramio)