poky: Add Fedora-20 to supported distros list

(From meta-yocto rev: cf42610ac26307f28d5b3fea6be8bde223c0ed40)

Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta-yocto/conf/distro/poky.conf

@@ -80,6 +80,7 @@ SANITY_TESTED_DISTROS ?= " \
             Ubuntu-13.10 \n \
             Fedora-18 \n \
             Fedora-19 \n \
+            Fedora-20 \n \
             CentOS-6.4 \n \
             Debian-6.0.7 \n \
             Debian-7.0 \n \