Support for GY-88 
 https://github.com/multiwii/multiwii-firmware/pull/10

git-svn-id: http://multiwii.googlecode.com/svn/trunk/MultiWii_shared@1691 02679b44-d973-9852-f2fa-63770883b36c
Merge pull request #1 from multiwii/upstream_shared

Support for GY-88