web: Add an npm link above the homepage fold

Add a third button underneath the INSTALL button that links
to http://search.npmjs.org

Fixes nodejs#4077.

doc/index.html

@@ -28,8 +28,9 @@
         <div class=buttons>
         <a href="http://nodejs.org/dist/__VERSION__/node-__VERSION__.tar.gz" class="button downloadbutton" id="downloadbutton">INSTALL</a>
 
-        <a href="download/" class=button id="all-dl-options">Downloads</a
-        ><a href="api/" class="button" id="docsbutton">API Docs</a>
+        <a href="download/" class=button id="all-dl-options">Downloads</a>
+        <a href="api/" class="button" id="docsbutton">API Docs</a>
+        <a href="http://search.npmjs.org" class="button" id="npmbutton">NPM</a>
         </div>
 
         <a href="http://github.com/joyent/node"><img class="forkme" src="http://nodejs.org/images/forkme.png" alt="Fork me on GitHub"></a>

doc/pipe.css

@@ -101,7 +101,7 @@ h1 a, h2 a, h3 a, h4 a {
   height: auto;
   overflow: hidden;
   _zoom: 1;
-  width: 300px;
+  width: 350px;
   margin: 0 auto;
 }
 
@@ -120,7 +120,7 @@ h1 a, h2 a, h3 a, h4 a {
   -moz-transition: .2s all ease-in-out;
   transition: .2s all ease-in-out;
 
-  margin: 10px 4px;
+  margin: 8px 1px;
   display: inline-block;
   color: #46483e;
   background-color: #9a9f8b;
@@ -145,7 +145,7 @@ h1 a, h2 a, h3 a, h4 a {
 
 #intro .downloadbutton {
   background-color: #8BC84B;
-  width: 200px;
+  width: 300px;
   font-size: 14px;
   font-weight: bold;
   display: block;