title: Cmake is not able to find Python-libraries
body: <p>Getting this error:</p>
  
  <pre><code>sudo: unable to resolve host coderw@ll
  -- Could NOT find PythonLibs (missing:  PYTHON_LIBRARIES PYTHON_INCLUDE_DIRS) 
  CMake Error at /usr/share/cmake-2.8/Modules/FindPackageHandleStandardArgs.cmake:108     
  (message):
  Could NOT find PythonInterp (missing: PYTHON_EXECUTABLE)
  Call Stack (most recent call first):
  /usr/share/cmake-2.8/Modules/FindPackageHandleStandardArgs.cmake:315  
  (_FPHSA_FAILURE_MESSAGE)
  /usr/share/cmake-2.8/Modules/FindPythonInterp.cmake:139 
  (FIND_PACKAGE_HANDLE_STANDARD_ARGS)
  Code/cmake/Modules/FindNumPy.cmake:10 (find_package)
  CMakeLists.txt:114 (find_package)
  
  
  
  -- Configuring incomplete, errors occurred!
  See also "/home/coderwall/Desktop/rdkit/build/CMakeFiles/CMakeOutput.log".
  See also "/home/coderwall/Desktop/rdkit/build/CMakeFiles/CMakeError.log".
  </code></pre>
  
  <p>I have already installed:</p>
  
  <ol>
  <li>sudo apt-get install python-dev</li>
  <li><p>Environment variable are already set as follow:</p>
  
  <pre><code>PYTHON_INCLUDE_DIRS=/usr/include/python2.7 
  PYTHON_LIBRARIES=/usr/lib/python2.7/config/libpython2.7.so
  </code></pre></li>
  </ol>
  
  <p>Location of <code>python.h</code> : <code>/usr/lib/include/python2.7/python.h</code></p>
  
  <p>Location of <code>python</code> libs: <code>/usr/lib/python2.7/</code>
  How to solve this? </p>