Fish config refactor

Move things into sub-files and sub-directories
Add ensure_path function to make sure stuff doesn't get spammed multiple
times into the PATH

fish/apps/rvm.fish

@@ -0,0 +1,35 @@
+function rvm --description='Ruby enVironment Manager'
+  # run RVM and capture the resulting environment
+  set --local env_file (mktemp -t rvm.fish.XXXXXXXXXX)
+  bash -c 'source ~/.rvm/scripts/rvm; rvm "$@"; status=$?; env > "$0"; exit $status' $env_file $argv
+
+  # apply rvm_* and *PATH variables from the captured environment
+  and eval (grep '^rvm\|^[^=]*PATH\|^GEM_HOME' $env_file | grep -v '_clr=' | sed '/^[^=]*PATH/y/:/ /; s/^/set -xg /; s/=/ /; s/$/ ;/; s/(//; s/)//')
+  # clean up
+  rm -f $env_file
+end
+
+function __handle_rvmrc_stuff --on-variable PWD
+  # Source a .rvmrc file in a directory after changing to it, if it exists.
+  # To disable this fature, set rvm_project_rvmrc=0 in $HOME/.rvmrc
+  if test "$rvm_project_rvmrc" != 0
+    set -l cwd $PWD
+    while true
+      if contains $cwd "" $HOME "/"
+        if test "$rvm_project_rvmrc_default" = 1
+          rvm default 1>/dev/null 2>&1
+        end
+        break
+      else
+        if begin; test -s ".rvmrc"; or test -s ".ruby-version"; or test -s ".ruby-gemset"; end
+          eval "rvm reload" > /dev/null
+          break
+        else
+          set cwd (dirname "$cwd")
+        end
+      end
+    end
+
+    set -e cwd
+  end
+end