BB feeds: switch packages feed to 14.07 branch

git-svn-id: svn://svn.openwrt.org/openwrt/branches/barrier_breaker@41886 3c298f89-4303-0410-b956-a3cf2f4a3e73

feeds.conf.default

-src-git packages https://github.com/openwrt/packages.git
+src-git packages https://github.com/openwrt/packages.git;for-14.07
 src-git luci http://git.openwrt.org/project/luci.git
 src-git routing https://github.com/openwrt-routing/packages.git
 src-git telephony http://git.openwrt.org/feed/telephony.git