Plugin installation does not perform update

Plugin installation just installs new plugins.
Already installed plugins aren't updated.

CHANGELOG.md

@@ -9,6 +9,8 @@
 - remove README 'about' section
 - move key binding to the main file. Delete `key_binding.sh`.
 - rename `display_message` -> `echo_message`
+- installing plugins installs just new plugins. Already installed plugins aren't
+  updated.
 
 ### v0.0.2, 2014-07-17
 - run all *.tmux plugin files as executables

scripts/sync_plugins.sh

@@ -52,14 +52,11 @@ pull_changes() {
 sync_plugin() {
 	local plugin=$1
 	if plugin_already_cloned "$plugin"; then
-		# plugin is already cloned - update it
-		echo_message "Updating $plugin"
-		pull_changes "$plugin" &&
-			echo_message "  $plugin update success" ||
-			echo_message "  $plugin update fail"
+		# plugin is already installed
+		echo_message "Already installed $plugin"
 	else
 		# plugin wasn't cloned so far - clone it
-		echo_message "Downloading $plugin"
+		echo_message "Installing $plugin"
 		clone_plugin "$plugin" &&
 			echo_message "  $plugin download success" ||
 			echo_message "  $plugin download fail"