Fix rply dependency.

To test this, replace the https://github.com/hylang/rply/zipball/master#egg=rply-0.6.2
url with https://github.com/berkerpeksag/rply/zipball/master#egg=rply-0.6.2
in setup.py.

$ cd hy
$ virtualenv dummy
$ . dummy/bin/activate
$ pip install .
$ pip install astor nose
$ make test
...
...
Ran 252 tests in 9.723s

OK