Make import more explicit in some notbook section

reimport HTML and Image in some place so that each of the subsection can
be ran independently

Also, link to python logo from subfolder to make the example directory
more packager friendly. The actual png file will be added in next commit

examples/notebooks/Part 5 - Rich Display System.ipynb

@@ -111,7 +111,7
      "cell_type": "code",
      "collapsed": false,
      "input": [
-      "i = Image(filename='../../docs/source/_static/logo.png')"
+      "i = Image(filename='logo/logo.png')"
      ],
      "language": "python",
      "metadata": {},
@@ -416,6 +416,8
      "cell_type": "code",
      "collapsed": false,
      "input": [
+      "from IPython.display import Image\n",
+      "\n",
       "# by default Image data are embedded\n",
       "Embed      = Image(    'http://scienceview.berkeley.edu/view/images/newview.jpg')\n",
       "\n",
@@ -1094,6 +1096,7
      "cell_type": "code",
      "collapsed": false,
      "input": [
+      "from IPython.display import HTML\n",
       "HTML('<iframe src=http://en.mobile.wikipedia.org/?useformat=mobile width=700 height=350></iframe>')"
      ],
      "language": "python",