Refs #1640 Adding jshrink to LEGALNOTICE + update help text

LEGALNOTICE

@@ -114,6 +114,10 @@ THIRD-PARTY COMPONENTS AND LIBRARIES
 	Notes:
 	- reference implementation
 
+	Name:  jshrink
+	Link: https://github.com/tedivm/jshrink
+	License: BSD-3-Clause
+
 	Name:  sparkline
 	Link:  https//sourceforge.net/projects/sparkline/
 	License:  Dual-licensed: New BSD or GPL v2

core/AssetManager/UIAssetMinifier.php

@@ -62,6 +62,6 @@ class UIAssetMinifier extends Singleton
     private static function validateDependency()
     {
         if (!class_exists("JShrink\Minifier"))
-            throw new Exception("JShrink dependency is managed using Composer.");
+            throw new Exception("JShrink dependency is managed using Composer. <br> $ php composer.phar update  ");
     }
 }

core/testMinimumPhpVersion.php

@@ -53,7 +53,7 @@ if ($minimumPhpInvalid) {
             . "<pre> curl -sS https://getcomposer.org/installer | php \n\n php composer.phar install\n\n</pre> ";
         if (DIRECTORY_SEPARATOR === '\\' /* ::isWindows() */) {
             $composerInstall = "Download and run <a href=\"https://getcomposer.org/Composer-Setup.exe\"><b>Composer-Setup.exe</b></a>, it will install the latest Composer version and set up your PATH so that you can just call composer from any directory in your command line. "
-                . " <br>Then run this command in a terminal in the piwik directory: <br> $ php composer update ";
+                . " <br>Then run this command in a terminal in the piwik directory: <br> $ php composer.phar update ";
         }
         $piwik_errorMessage .= "<p>It appears the <a href='https://getcomposer.org/' target='_blank'>composer</a> tool is not yet installed. You can install Composer in a few easy steps:\n\n".
                     "<br/>" . $composerInstall.