[tools/grep-all.sh] Get branches from git

Rather than hard code the branches to look at just do all the stable
branches that exist.

Change-Id: I8beb6ed5e537f37e707d1e04ad9c1174fd608544

tools/grep-all.sh

@@ -14,12 +14,8 @@
 
 # Note(tonyb): Expand HEAD into something that's hopefully more human
 #              readable
-declare -a branches=(
-                        $(git describe --always) origin/master
-                        origin/stable/pike
-                        origin/stable/ocata
-                        origin/stable/newton
-                    )
+declare -a branches=($(git describe --always) origin/master)
+branches+=($(git branch --no-color -r --list 'origin/stable/*'))
 
 function search {
     git grep -hEi "^${1}[=><!]" ${2} -- "${3}"