fixing broken links

Author: antmarakis

intro.ipynb

@@ -17,9 +17,9 @@
     "  \n",
     "## What version of Python?\n",
     "  \n",
-    "The code is tested in Python [3.4](https://www.python.org/download/releases/3.4.3/) and [3.5](https://www.python.org/downloads/release/python-351/). If you try a different version of Python 3 and find a problem, please report it as an [Issue](https://github.com/aimacode/aima-python/issues). There is an incomplete [legacy branch](https://github.com/aimacode/aima-python/tree/aima3python2) for those who must run in Python 2. \n",
+    "The code is tested in Python [3.4](https://www.python.org/download/releases/3.4.3/) and [3.5](https://www.python.org/downloads/release/python-351/). If you try a different version of Python 3 and find a problem, please report it as an [Issue](https://github.com/aimacode/aima-python/issues).\n",
     "  \n",
-    "We recommend the [Anaconda](https://www.continuum.io/downloads) distribution of Python 3.5. It comes with additional tools like the powerful IPython interpreter, the Jupyter Notebook and many helpful packages for scientific computing. After installing Anaconda, you will be good to go to run all the code and all the IPython notebooks. \n",
+    "We recommend the [Anaconda](https://www.anaconda.com/download/) distribution of Python 3.5. It comes with additional tools like the powerful IPython interpreter, the Jupyter Notebook and many helpful packages for scientific computing. After installing Anaconda, you will be good to go to run all the code and all the IPython notebooks. \n",
     "\n",
     "## IPython notebooks  \n",
     "  \n",