poky.conf: Bump for 2.1 development

(From meta-yocto rev: 45dd622d7447050e0c9caa067cce87d125518117)

Signed-off-by: Beth Flanagan <elizabeth.flanagan@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta-yocto/conf/distro/poky.conf

 DISTRO = "poky"
 DISTRO_NAME = "Poky (Yocto Project Reference Distro)"
-DISTRO_VERSION = "2.0"
-DISTRO_CODENAME = "jethro"
+DISTRO_VERSION = "2.0+snapshot-${DATE}"
+DISTRO_CODENAME = "master"
 SDK_VENDOR = "-pokysdk"
 SDK_VERSION := "${@'${DISTRO_VERSION}'.replace('snapshot-${DATE}','snapshot')}"