Add qrcode==5.0.1 and pillow>=2.6.1 to Pip requirements.txt file.

Pillow, in Debian jessie, is in the `python-imaging` package (currently
version 2.6.1).  However, on PyPI, Pillow is simply `pillow` (currently
version 2.7.0). Both of these are backwards compatible with the
python-imaging package in Debian wheezy (currently version 1.1.6, and
likely to never get updated, because it is being replaced with pillow).
And any of these will currently work with BridgeDB.

requirements.txt

@@ -7,5 +7,7 @@ pycrypto==2.6.1
 pyOpenSSL==0.13.1
 pygeoip==0.2.7
 pygpgme==0.3
+pillow>=2.6.1
+qrcode==5.0.1
 recaptcha-client==1.0.6
 zope.interface==3.6.1