Install user-specific bins

- Install diff-highlight in to $HOME/bin

script/install

@@ -21,3 +21,5 @@ for source in "$HOME/.bin/"*; do
     ln -sv "$source" "$target"
   fi
 done
+
+source "$DOTFILES_DIR/script/install-user-bins.sh"

script/install-user-bins.sh

@@ -0,0 +1,14 @@
+#!/bin/bash
+
+# Install diff-highlight on Ubuntu/Debian
+if [[ -f /usr/share/doc/git/contrib/diff-highlight/diff-highlight ]]
+  then
+    cp -uv /usr/share/doc/git/contrib/diff-highlight/diff-highlight "$HOME/bin"
+    chmod u+x "$HOME/bin/diff-highlight"
+fi
+
+# Install diff-highlight on OS X
+if [[ -f /usr/local/Library/LinkedKegs/git/share/git-core/contrib/diff-highlight/diff-highlight ]]
+  then
+    ln -sf /usr/local/Library/LinkedKegs/git/share/git-core/contrib/diff-highlight/diff-highlight "$HOME/bin/diff-highlight"
+fi