fix up our script for extracting the git version

Author: agilliland

bin/version

@@ -2,9 +2,10 @@
 
 # Return the version string used to describe this version of Metabase.
 
-TAG=$(git describe origin/master --tags --abbrev=0)
+TAG=$(git name-rev --tags --name-only HEAD)
+TAG=${TAG%^0}
 HASH=$(git show-ref --head --hash=7 head)            # first 7 letters of hash should be enough; that's what GitHub uses
-BRANCH=$(git symbolic-ref --short HEAD)
+BRANCH=$(git rev-parse --abbrev-ref HEAD)
 DATE=$(git log -1 --pretty=%ad --date=short)
 
 echo "$TAG $HASH $BRANCH $DATE"