Reverted lettuce to v1.35

Whilst following installation instructions I can across the error:

    IOError: [Errno 2] No such file or directory: u'/home/ralph/.virtualenvs/test/build/sure/readme.rst'
    
    ---------------------------------------- 
    Cleaning up...
    Command python setup.py egg_info failed with error code 1 in /home/ralph/.virtualenvs/test/build/sure
    Storing debug log for failure in /home/ralph/.pip/pip.log

The issue stemmed from the lettuce package. Versions 2.x+ produce an error, I downgraded the version and installation worked.