Undeclared dependency on grako

[shreevatsa]

% shakespeare run echo.spl
Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/2.7/bin/shakespeare", line 7, in <module>
    from shakespearelang.cli import main
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/shakespearelang/cli.py", line 4, in <module>
    from .shakespeare_interpreter import Shakespeare
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/shakespearelang/shakespeare_interpreter.py", line 5, in <module>
    from .shakespeare_parser import shakespeareParser
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/shakespearelang/shakespeare_parser.py", line 16, in <module>
    from grako.buffering import Buffer
ImportError: No module named grako.buffering

I was able to work around this with pip install grako, but the package should probably declare this dependency.