managed multi-user install location for rvm.fish

plugins/rvm/rvm.fish

@@ -1,7 +1,7 @@
 function rvm -d 'Ruby enVironment Manager'
   # run RVM and capture the resulting environment
   set -l env_file (mktemp -t rvm.fish.XXXXXXXXXX)
-  bash -c 'source ~/.rvm/scripts/rvm; cd .;rvm "$@"; status=$?; env > "$0"; exit $status' $env_file $argv
+  bash -c '[ -e ~/.rvm/scripts/rvm ] && source ~/.rvm/scripts/rvm || source /usr/local/rvm/scripts/rvm; cd .;rvm "$@"; status=$?; env > "$0"; exit $status' $env_file $argv
 
   # apply rvm_* *PATH RUBY_* GEM_* variables from the captured environment
   and eval (grep '^rvm\|^[^=]*PATH\|^RUBY_\|^GEM_' $env_file |grep -v _clr| sed '/^[^=]*PATH/y/:/ /; s/^/set -xg /; s/=/ /; s/$/ ;/; s/(//; s/)//')